Most was born in Aldershot, Hampshire. The son of a regimental sergeant-major, he moved with his parents to the north London suburb of Harrow in 1951. Most was influenced by skiffle and early rock 'n' roll in his youth. Leaving school at 15, he worked as a singing waiter at London's The 2i's Coffee Bar where he made friends with future business partner Peter Grant, and formed a singing duo with Alex Wharton (aka Alex Murray) who billed themselves as The Most Brothers. They scored a minor hit with Decca Records called "Takes a Whole Lotta Loving to Keep My Baby Happy" before disbanding. Wharton went on to produce the Moody Blues single "Go Now". After changing his name to Mickie Most in 1959, he travelled to South Africa with his wife Christina, and formed a pop group, Mickie Most and the Playboys. The band scored 11 consecutive Number 1 singles playing mostly cover versions of Ray Peterson, Gene Vincent, Buddy Holly and Eddie Cochran. Returning to London in 1962, Most appeared on package tours as well as recording "Mister Porter", a minor hit in 1963.
Becoming tired of touring clubs, Most decided to concentrate on other aspects of the music industry. His first job was selling records in stores and displaying them on racks (later inspiration for his record label, RAK) before finding a niche with production for Columbia Records. After spotting The Animals at Newcastle's Club A-Go-Go, he offered to produce their first single, "Baby Let Me Take You Home", which reached Number 21 on the UK charts. Their follow-up 1964 single, "The House of the Rising Sun", became a worldwide hit. Most then won the "Producer of the Year" award at the 1964 Grammy Awards.
Most had instant success with Manchester band Herman's Hermits after being approached by their manager Harvey Lisberg. Their first Most production, "I'm Into Something Good", went to #1 in 1964, beginning a run of single and album sales (ten million over 12 months), the group for a time challenging The Beatles in popularity in the United States. His down-to-earth handling of the band, his business acumen and knack for selecting hit singles established Most as one of the most successful producers in Britain and kept him in demand throughout the 1960s and 1970s.
In September 1964, with Most at the control board, Brenda Lee recorded "Is It True," and "What'd I Say," "Is It True," was released in England, and later in the U.S. and became a hit, with gold record. "What'd I Say," became another hit throughout Europe, but was never released to the U.S. Most had equal success with other artists for whom he produced chart-topping albums and singles between 1965 and 1969, notably Donovan with "Mellow Yellow", "Jennifer Juniper", "The Hurdy Gurdy Man", and "Atlantis" and Lulu "To Sir, with Love", "The Boat That I Row", "Boom Bang-A-Bang" (which finished equal first in the 1969 Eurovision Song Contest), "Me the Peaceful Heart", and "I'm a Tiger". Most also produced The Seekers singles "Days of My Life" and "Love Is Kind, Love Is Wine", in 1968, and Nancy Sinatra’s "The Highway Song" in 1969.
Most's productions were backed by London session musicians including Big Jim Sullivan and Jimmy Page on guitar, John Paul Jones on bass guitar and arrangements, and Nicky Hopkins on piano. He produced Jeff Beck's hits "Love is Blue" and "Hi Ho Silver Lining" and the Jeff Beck Group LPs Truth and Beck-Ola, teamed the Beck group with Donovan for the single "Goo Goo Barabajagal", and signed new artists such as singer-guitarist Terry Reid.
By 1967 music was turning to a heavier and improvisational sound at odds with Most's formulaic singles selection format. After commercial and critical failure of The Yardbirds album Little Games, he decided to steer clear of rock groups, realizing they mostly did not share his vision. The Yardbirds objected to his insistence that every song be cut to three minutes and that albums were an "afterthought" following the singles. His focussed approach also led to a split with Donovan in late 1969.
Despite these setbacks, Most set up his own production office at 155 Oxford Street, sharing it with his business partner Peter Grant. It was through Most's association that Grant was asked to manage The Yardbirds. In 1968, Most and Grant set up RAK Management, but Grant's involvement with The Yardbirds, which soon evolved into Led Zeppelin, meant Most had control in late 1969. RAK Records and RAK Music Publishing were launched in 1969. RAK music publishing has the copyright of such classic popular songs as "You Sexy Thing" composed by Hot Chocolate singer Errol Brown and a half interest in the song "I Love Rock 'n' Roll" written by Alan Merrill and Jake Hooker of the band The Arrows. Both acts were produced by Most.
With RAK Records, Most's success continued with folk singer Julie Felix's hit "El Condor Pasa". Felix was the first artist signed to the label. Most then produced Mary Hopkin’s 1970 Eurovision Song Contest entry, "Knock Knock Who's There?," followed by the single "Temma Harbour". In 1970, Most approached Suzi Quatro for a recording contract after seeing her on stage at a Detroit dance hall with the band Cradle (which also had Quatro’s sisters Arlene, Patti, and Nancy as members), while on a production assignment in Chicago. Quatro was among a growing roster of artists signed to RAK Records which included Alexis Korner's CCS, The Arrows, Hot Chocolate, Angie Miller, and Chris Spedding. Hiring the songwriting production team of Nicky Chinn and Mike Chapman, RAK scored several British #1 singles with Suzi Quatro ("Can the Can", "Devil Gate Drive"), Sweet, and Mud.
In 1976, Most produced Chris Spedding's self-titled album "Chris Spedding", which was Spedding's first solo record.
In 1980, Mickie Most discovered Kim Wilde, who was doing backing vocals for her father Marty Wilde at a Luton recording session. After hearing her Most signed Wilde and produced the single "Kids In America" which reached Number 2 in the UK and other countries, and Number 25 on the US Billboard charts.
Most was a panelist on television talent shows such as ITV's New Faces where his tough assessments of contestants foreshadowed the style of Simon Cowell. He was producer of Revolver, a program devoted to punk rock which was at odds with his "studio factory" approach to music. Most asked Kate Bush to appear as guest on the pilot episode. In the 1980s, the band Johnny Hates Jazz, which featured Most's son Calvin Hayes, was also signed to RAK Records. RAK sold out to EMI in 1983 but revived in 1988. Most was one of the first producers to own the rights to his own records and RAK Studios, opened in 1976 in St John's Wood, remains active
In 1995, Most's fortune was estimated at £50 million and he appeared in the Sunday Times annual Rich List among the Top 500 in England. His house in Totteridge Lane, London N20 was claimed to be the largest private home in UK worth an estimated £4 million. His production work diminished after cancer in 2000.
On 30 May 2003 Most died at home of mesothelioma, a cancer almost always caused by exposure to asbestos, and was cremated at Golders Green crematorium in north London. He is survived by his wife Christina and their three children Calvin, Nathalie, and Crystalle.