The Moody Blues formed on 4 May 1964, in Erdington, Birmingham, England. Ray Thomas, John Lodge, and Michael Pinder had been members of El Riot & the Rebels, a regionally-popular band. They disbanded when Lodge, the youngest member, went to technical college and Pinder joined the army. Pinder then rejoined Thomas to form the Krew Cats and enjoyed moderate success. The pair recruited guitarist/vocalist Denny Laine, band manager-turned drummer Graeme Edge, and bassist Clint Warwick. The five appeared as the Moody Blues for the first time in Birmingham in 1964. The name developed from a planned sponsorship from the M&B Brewery and was also a subtle reference to the Duke Ellington song, "Mood Indigo" .

Soon, the band obtained a London-based management company, 'Ridgepride', formed by ex-Decca A&R man Alex Murray (Alex Wharton), who helped them land a recording contract with Decca Records in the spring of 1964. They released a single, "Steal Your Heart Away" that year which made it onto the charts. But it was their second single, "Go Now" (released later that year), which really launched their career, being promoted on TV with one of the first purpose-made promotional films in the pop era, produced and directed by Wharton. The single became a hit in the United Kingdom (where it remains their only Number 1 single to date) and in the United States where it reached #10.

Their debut album The Magnificent Moodies, produced by Denny Cordell with a strong Merseybeat/R and B flavour, was released on Decca in 1965. It contained the hit single together with one side of classic R and B covers, and a second including four Laine/Pinder originals.

Wharton left the management firm and the group released a series of unsuccessful singles. In the summer of 1966, Warwick left the group. He was briefly replaced by Rod Clark but by October, Laine and Clark had also departed the group. They were immediately replaced by John Lodge, their bassist from El Riot, and Justin Hayward, formerly of The Wilde Three. Pinder phoned Hayward after reading his application to The Animals, and was impressed when Hayward played him his 45 rpm single "London is Behind Me" during their car ride to meet the other members in Isha. After financial misfortune and a confrontation from an audience member, the band soon realised that their style of American blues covers and novelty tunes was not working for them, and they decided that they would only perform their own material. Their new style, featuring the symphonic sounds of Pinder's mellotron and Ray Thomas' flute, and incorporating distinct psychedelic influences, was to be developed in a concept album revolving around an archetypal day in the life of everyman.

The Moody Blues' contract with Decca Records was set to expire and they owed the label several thousand pounds in advances. However, they had the support of Decca A&R manager Hugh Mendl, who had been instrumental in the recent establishment of London/Decca's new subsidiary imprint Deram Records. With Mendl's backing, The Moody Blues were offered a deal to to make a rock and roll version of Antonín Dvořák's New World Symphony that would promote the company's new Deramic Stereo Sound (DSS) format, in return for which the group would be forgiven its debt.

The Moody Blues agreed, but they insisted that they be given artistic control of the project, and Mendl (as executive producer) was able to provide this in the face of Decca's notoriously tight-fisted attitude to its artists. The group were unable to complete the assigned project, which was abandoned, and they managed to convince Peter Knight, who had been assigned to arrange and conduct the orchestral interludes, to collaborate on a recording that used the band's original material instead.

Deram executives were initially sceptical about the hybrid style of the resulting concept album, but Days of Future Passed (released in November 1967) became one of the most successful pop/rock releases of the period, earning a gold record award and reaching #3 on the British album chart. The album was a song cycle that (like James Joyce's Ulysses) took place over the course of a single day. In production and arrangement it drew inspiration from the pioneering use of the classical instrumentation by The Beatles, but took the form to new heights, using the London Festival Orchestra to provide full orchestral backing throughout the album, combined with rock instrumentation, centred on Pinder's Mellotron.

Decca staff producer Tony Clarke was chosen to produce the album, and the band carried on a durable working relationship with Clarke (sometimes known to fans as "the sixth Moody") who went on to produce all of their albums and singles for the next eleven years. Engineer Derek Varnals would also contribute heavily to the creation of the early Moodies' studio sound.

The album plus two singles, "Nights in White Satin" and "Tuesday Afternoon" (known as "Forever Afternoon (Tuesday?)" on the album), became massively popular, as was the 1968 follow-up LP, In Search of the Lost Chord. Also included on this album is the song "Legend of a Mind", a song written by Ray Thomas in tribute to LSD guru Timothy Leary which encompassed a masterful flute solo performed by Thomas. Justin Hayward began playing sitar and incorporating it into Moody Blues music, having been inspired by George Harrison. Graeme Edge found a significant secondary role in the band as a writer of poetry, and nearly all of their early albums from the late Sixties begin with Mike Pinder reciting poems by Edge that were conceptually related to the lyrics of the songs that would follow. The band's music continued to become more complex and symphonic, with heavy amounts of reverberation on the vocal tracks, resulting in 1969's To Our Children's Children's Children — a concept album based around the band's celebration of the first moon landing. The album closes with "Watching and Waiting", composed by Ray Thomas and Justin Hayward.

Although the Moodies had by now defined a somewhat psychedelic style and helped to define the progressive rock (then also known as 'art rock') sound, the group decided to record an album that could be played in concert, losing some of their full-blown sound for, A Question of Balance (1970). This album, reaching #3 in the American charts and #1 in the British charts, was indicative of the band's growing success in America. Justin Hayward began an artful exploration of guitar tone through the use of numerous effects pedals and fuzz-boxes, and developed for himself a very melodic buzzing guitar-solo sound. For their next two albums, Every Good Boy Deserves Favour (1971) and Seventh Sojourn (1972) (which reached #1 in the U.S.), the band returned to their signature orchestral sound which, while difficult to reproduce in concert, had become their trademark. Edge, the long standing drummer-poet, started writing lyrics intended to be sung, rather than verses to be spoken.

In late 1972, a re-issue of the five-year-old "Nights In White Satin" became the Moody Blues' biggest U.S. hit, soaring to number two on the Billboard Hot 100 and becoming a certified million-seller; the song had "bubbled under" the Hot 100 charts on its original release. The song also returned to the UK charts, reaching #9, ten places higher than its original release in 1967.

The Moodies were also among the pioneers of the idea that a successful rock band could promote itself through its own label, following the Beatles' creation of Apple Records. After their On the Threshold of a Dream album (1969), they created Threshold Records, prompted in part by disputes with London/Deram over album design costs (their gatefold record jackets and expensive cover art were not popular with company executives). Threshold would produce new albums and deliver them to London/Decca who acted as distributor. The group attempted to build Threshold into a major label by developing new talent — most notably the UK hard rock band Trapeze and the Portland, Oregon classical-acoustic sextet Providence — but these efforts proved unsuccessful and the Moodies eventually returned to more traditional recording contracts. However, they did lay the groundwork for other major acts to set up similar personal labels and distribution deals including The Rolling Stones' own label and Led Zeppelin's Swan Song, and all of the Moodies' studio releases from 1969 to 1999 would bear the Threshold logo on at least one of their format versions.

In the spring of 1974, after completing a tour of Asia, the group took an extended break — originally announced as a permanent break-up — Justin Hayward being the only one eager to go on. By this point the other band members were feeling exhausted and overshadowed. (This said by Justin himself in the final issue of Higher & Higher magazine 2006). Prior to the band's 1973-74 world tour, Hayward wrote a song called "Island" with the intention of including it on a potential follow-up album, which the Moodies recorded in 1973 before ultimately going their separate ways. During 1974, the compilation album This Is The Moody Blues was released by Threshold Records.

Hayward and Lodge released a duo album, the very successful Blue Jays (1975), and the members each released solo albums. Pinder said he hoped to get the band back together that year. "Having moved to California in 1974, I returned to England for a visit in summer 1975. I was trying to get the band to do an album, but the response was so weak I returned to California with my two new MK5 mellotrons and began work on my solo album The Promise.".

Edge produced two albums with guitarist Adrian Gurvitz, Kick Off Your Muddy Boots (1975) and Paradise Ballroom (1976); Hayward composed the acoustically textured Songwriter (1977), which would be followed up in later years by Night Flight (1980), Moving Mountains (1985), Classic Blue (1989), The View From The Hill (1996), and Live In San Juan Capistrano (1998); Lodge released Natural Avenue (1977); Pinder produced The Promise (1976); and Thomas collaborated on two projects with songwriter Nicky James, producing From Mighty Oaks (1975) and Hopes, Wishes and Dreams (1976).

In 1977, as the group made a decision to record together again, London Records decided to release a somewhat poorly mixed then-eight year old recording of the band performing at the Royal Albert Hall, against their artistic wishes. London did this in an attempt to re-energize a somewhat waning public interest in the Moody Blues prior to their anticipated new album, but the crude sound of the concert from 1969 titled Caught Live + 5 would clash sharply with the lush and refined sound the modern Moodies were capable of producing in the studio. By this time Pinder had married and started a family in California, so for their reunion recording, the band decamped stateside with producer Clarke. The sessions were marked with tension and division (with Pinder dropping out before completion), but by the spring of 1978 Octave was ready for release. Pinder, citing his young family, excused himself from the touring commitments that were to follow.

During this period, the prog-rock band Yes had asked their keyboard player, Patrick Moraz, to leave. Moraz's management had some contacts with the Moodies, and after a successful audition with the band in England in 1978, he was hired as keyboard player for the Octave World Tour that began in Germany in October. In spite of these difficulties, the album itself sold well and produced the hits "Steppin' In a Slide Zone", written by Lodge and "Driftwood", written by Hayward. The music video produced for "Driftwood" features Moraz, although Mike Pinder was the one who played on the actual recording; the video for "Steppin' In A Slide Zone" simply shows the other four members without Pinder.

The Moodies toured the U.S. and Europe during much of 1979. By 1980 they were ready to record again, this time bringing in producer Pip Williams. Moraz was retained as the band's permanent keyboardist, though Pinder had originally understood that he would continue to record even if not tour with the band. Pinder attempted legal measures to prevent the new Moody Blues album from reaching the public without his contribution, but he was not successful, and ultimately, he never returned to the fold. Released in 1981, Long Distance Voyager was a colossal success, reaching #1 on Billboard and top 5 in the UK. The album yielded two hits, "The Voice", written by Hayward, and "Gemini Dream", written by Hayward and Lodge. By now, the mellotron had been set aside as their primary keyboard instrument and the band embraced a more modern, less symphonic approach. The marketing formula for the band demanded from this time forward that a Justin Hayward song would be used to lead off their studio albums, as his material was the most popular.

The Present (1983), again produced by Williams, proved less successful than its predecessor, though it did spawn a UK top 40 hit in "Blue World" (#62 in the U.S.) and a U.S. top 40 hit in "Sitting at the Wheel" (which failed to chart in the UK). Videos were also produced for both singles. "The Present" was released in conjunction with Talencora Ltd. Records shortly before Decca was bought out by Polydor Records.

In 1986 they enjoyed renewed success with their album The Other Side of Life and in particular with the track, "Your Wildest Dreams" - a U.S. Top 10 hit (and #1 on Billboard's Adult Contemporary singles chart for two weeks) which garnered a Billboard Video of the Year award after being frequently featured on MTV. Newly-hired producer Tony Visconti, and Barry Radman, a synth programmer formerly hired by Moraz, delivered a modern sound the Moodies had been after in order to remain competitive with their pop contemporaries. The album's title song also charted in the U.S., at #58.

The Moody Blues performed live at the charity event concert "Heartbeat '86" which raised money for the Birmingham Children's Hospital. The band played four songs, and later provided backup with Electric Light Orchestra for George Harrison.

The Moodies continued their early video-generation success with Sur La Mer (1988) and its video/single, "I Know You're Out There Somewhere", a sequel to "Your Wildest Dreams". Their sound took on an ever- increasingly synthetic and technical quality as Moraz and Visconti began utilising modern sequencers, samplers, and drum machines. During this time, Justin Hayward and John Lodge wrote and sang on most of the songs as the band came under pressure from the new record company, PolyGram Records, to promote those it deemed to be the two more commercial looking and sounding members. Ray Thomas was playing a diminished role in the studio. The band were temporarily evolving into a synthpop act, with music not at all fit for a flute, and he was relegated to the status of a backup singer. He provided some backing vocals for both The Other Side of Life and Sur La Mer. Multiple production considerations led Visconti to leave Thomas' vocals off of the latter of these two albums.

Thomas' high value remained on stage primarily from his continued ability to sing out his 60's and 70's Moodies classics, and also in flute and keyboard duets he composed with Moraz which were only performed by the two during Moodies' concerts. The band had begun to reinforce their concert sound in the mid-to-late 1980s with the addition of a second keyboardist, Bias Boshell (soon replaced by Guy Allison), as well as female backing singers.

In 1991, halfway through the production of their new studio album, Patrick Moraz made some comments in an article in Keyboard magazine that suggested dissatisfaction with his role in the Moodies. His complaints ranged from the Moodies' music becoming too simple in structure, to the other members' reluctance to allow him to make significant contributions to the songwriting on their albums. He also was spending long amounts of time planning a music concert to celebrate his native Switzerland's 700th anniversary, instead of rehearsing with the Moodies. He was dismissed from further participation in the group before the project was completed. Additional back-up keyboardists Bias Boshell and Paul Bliss were brought in to play keyboards on the remaining tracks.

Keys of the Kingdom (1991) had modest commercial success. It featured the new single "Say It With Love" and its follow-up "Bless the Wings" as well as a new flute masterpiece by Ray Thomas entitled "Celtic Sonant." John Lodge would make a defining shift in his songwriting on this album, leaving his trademark high-energy rock music, and instead gravitating towards slow love ballads. This trend would continue on the two successive Moodies albums. Instead it was Hayward who wrote the driving two-part piece "Say What You Mean" which featured compelling chord and melody structures as well as a spoken-word section. Tony Visconti produced some of the tracks on "Keys", as did Christopher Neil and Alan Tarney.

For touring purposes, the band decided not to hire a permanent replacement in the keyboard chair but instead to tour as a quartet with extra hired musicians. Following on from his contributions as keyboardist/programmer on the 'Keys Of The Kingdom' album, Paul Bliss has consistently fulfilled keyboard duties with the band on-stage since 1991, recreating the Mike Pinder and Patrick Moraz sound live with the Moody Blues. Thomas and Bliss continued the tradition of a flute/keyboard duet for many tours. The band also enlisted a second drummer, Gordon Marshall, who accompanies the group on concert tours to this day.

The Moodies remained among the highest-earning concert acts, and a series of video and audio versions of their 1992 Night at Red Rocks concert enjoyed great success, particularly as a fund-raiser for American public television where it had been first broadcast, it was also conducted and composed by Larry Baird, who has helped many other bands like Kansas, Michael Bolton, and Three Dog Night, Al Jarreau, and Alan Parsons in orchestral form of live events. They were also invited to play at the annual Montreux Jazz Festival in Switzerland the year prior, which they did in support of their Keys of the Kingdom album release.

1994 saw the release of one of their many career spanning compilations, a 5-CD collection called "Time Traveller." During the same year, Mike Pinder would release his second solo album Among the Stars. Pinder would ultimately find a new niche in recording world music-backed children's stories on CD.

Instead of beginning on a new studio project, the Moodies would instead attempt to perfect the art of playing with an orchestra during these years, working with several talented orchestral ensembles and trying new arrangements for well-known pieces. Their second hiatus from recording ended in 1998.

Their first studio album in eight years, Strange Times (1999), proved to be the first Moodies album in almost two decades to be more than moderately received by UK critics; the album was released by Universal Music Group, which is the new identity of Decca Records. It was recorded in a studio in Recco, Italy, at Hayward's suggestion, and was produced by the Moodies themselves - attesting to their 3 decades of recording experience. This album was the first to feature Danilo Madonia as an arranger and electric organist. Madonia would go on to play keyboards on all future Moodies studio tracks, including on the follow-up album, "December". The CD opened with the unusual "English Sunset", an RPM techno song written by Justin Hayward. Strange Times was also the first album since 1970 to include a new poem by Graeme Edge.

Also in 1999, The Moody Blues appeared in one episode of "The Simpsons" called "Viva Ned Flanders".

In 2000, the band released "Hall of Fame", a new live concert from Royal Albert Hall on the Ark 21 label.

In 2001, an IMAX film was released, entitled "Journey into Amazing Caves", which featured two new songs written and performed by the Moody Blues. The soundtrack also featured Justin Hayward performing vocals and playing guitar throughout. One of these songs, entitled "Water", is the Moody Blues' first instrumental studio recording since their 1983 piece "Hole in the World" from The Present LP.

The new millennium saw the Moody Blues reducing their touring schedule. At the end of 2002, founding member Ray Thomas retired from the group, reducing The Moody Blues to the trio of Hayward, Lodge, and Edge. Flutist Norda Mullen was recruited early the following year for their North America tour, and has been a versatile player on-stage and in the studio in Thomas' stead ever since. Toward the end of 2003, and without the participation of Thomas, they released a Christmas-themed album entitled December. The songs included originals and covers such as John Lennon's "Happy Xmas (War Is Over)".

Original bassist Clint Warwick, who had left the group in 1966 to become a carpenter and raise a family, returned to the music scene in 2002 and released a solo CD. He died of liver disease on May 15, 2004.

On October 23, 2005, Hayward, Lodge, and Edge joined Tennessee musicians David Harvey, Tim O'Brien, John Cowan, and others for a concert of "Moody Bluegrass" at the Ryman Auditorium in Nashville; the Moodies had been impressed by the group's CD of the same name featuring well-known MB songs interpreted in bluegrass style.

In November 2005, Hayward, Lodge, and Edge - accompanied by Norda Mullen, Gordon Marshall, Paul Bliss and second keyboard player Bernie Barlow released a live-DVD, entitled Lovely to See You: Live, recorded at the Greek Theatre in Los Angeles.

The remaining Moody Blues trio continues to tour. They toured the U.S. and Canada in 2007 and 2008.

In addition, Hayward took part in the UK tour of Jeff Wayne's Musical Version of The War of the Worlds in April 2006, and a second tour in November 2007.

In March 2006, the first five of the band's 'Core 7' albums (the seven albums from Days of Future Passed to Seventh Sojourn, inclusive) were re-released in Super Audio CD format with Deluxe Editions, featuring bonus songs and some rare previously unreleased tracks by the group. In April 2007, the last two of these classic albums were re-released by Universal/Threshold. These deluxe editions were unique for an art rock group like the Moodies in that one of their members, Justin Hayward, was the one hired to do the work, instead of a professional masters technician. Hayward stated that he listened to virgin vinyl copies of these albums and used them as reference points for the new compact discs. In September 2008, Hayward announced via his website that remastered versions of Octave, Long Distance Voyager, and surprisingly, The Present will be released on Universal records in the months to come.

Bassist John Lodge has said in an interview on the radio show "Acoustic Storm" on January 30, 2007 that a new Moody Blues album is "not far away."

On May 21, 2007 the Moodies released a forty one track, two-disc compilation of sessions recorded at BBC Studios, various television appearances, and a previously 'lost' performance done on the Tom Jones show titled Live at the BBC 1967-1970.

On October 31, 2007, the Hard Rock Park theme park announced that they are building a dark ride based on "Nights in White Satin" called "Nights in White Satin - The Trip". The ride will incorporate sights, sounds, smells and tactile technique, as well as a re-orchestrated version of the song by Justin Hayward. A re-recorded version of Graeme Edge's "Late Lament" again follows. This version, however, has Edge, Lodge, and Hayward each reading a verse of the poem.

In January 2008 the Moody Blues announced a 15 date UK tour for September & October 2008. . An extra date at the Royal Albert Hall was added to deal with public demand.