Walter M. Booker Jr. was born December 17, 1933, in Prairie View, Texas. His family moved to Washington, D.C. in the mid-1940s, where he studied clarinet and alto saxophone in a college concert band before switching to bass in 1959 during a hitch in the U.S. Army, where he served in the same unit as Elvis Presley. After his discharge he fell in with Washington's jazz scene, joining saxophonist Andrew White's JFK Quintet and touring with the Shirley Horn Trio alongside drummer Billy Hart.

Booker moved to New York City in 1964, where trumpeter Donald Byrd hired him almost immediately, and where he studied bass with Homer Mensch at Juilliard. Through the rest of the 1960s he became one of the city's most reliable freelance bassists, recording with Sonny Rollins (On Impulse!, 1965; the Alfie film score, 1966), Milt Jackson (Born Free, 1967), Stan Getz (What the World Needs Now, 1968), Betty Carter, Art Farmer, and Ray Bryant, and touring and recording with Thelonious Monk's last working group in the late 1960s. He also appears, credited on bass, on Pete La Roca's 1967 quartet date Turkish Women at the Bath (Douglas Records, later reissued as Bliss! and, in Europe, as Chick Corea's Love Planet), alongside pianist Chick Corea and tenor saxophonist John Gilmore. On Wayne Shorter's 1970 Blue Note album Super Nova he switched instruments entirely, playing classical guitar rather than bass (Miroslav Vitous held that chair); his first wife, Maria Booker, sings on the same session, on the track "Dindi." The marriage did not survive it.

In 1969, Cannonball Adderley hired Booker for his working quintet, and it became the defining association of his career. Booker toured the world with Cannonball, Nat Adderley, pianist Joe Zawinul and later George Duke, and drummer Roy McCurdy for six years, appearing on Country Preacher (1970, recorded live at a Chicago church benefit for Jesse Jackson's Operation Breadbasket), The Black Messiah (1971), Inside Straight (1973), and Pyramid (1974), among others. Booker also had his own showcase in the band's live book: "Soli Tomba," a feature built on his bowed and sung bass playing, documented on the group's October 25, 1972 concert at the Paris Olympia (unreleased until 2024, as Poppin' in Paris). He remained with Cannonball until the saxophonist's death in August 1975.

From 1975 to 1981, Booker was the bassist for singer Sarah Vaughan, a stint documented on the 1978 New Orleans concert recording Live at Rosy's (issued by Resonance Records in 2016). During and after the Vaughan years he designed, built, and ran his own Boogie Woogie Studio in New York, which became a gathering place for musicians and helped launch younger groups such as Natural Essence, and he led Brazilian-tinged bands of his own called Love Carnival and Dreams. Through the 1980s and 1990s he became pianist John Hicks's regular bassist, co-billed on Some Other Time (1981), Inc.1 (1985), and Gentle Rain (1995), and he kept working steadily with Nat Adderley's own quintet and sextet (We Remember Cannon, 1989; Autumn Leaves and Work Song, both recorded live at Sweet Basil in 1991), as well as with Pharoah Sanders, Nick Brignola, Clifford Jordan, Archie Shepp, and trumpeter Roy Hargrove, on whose 1995 album Family he plays bass on four tracks. He married pianist Bertha Hope, the widow of pianist Elmo Hope, and became a regular member of her trio, recording In Search of... Hope (1991), Between Two Kings (1992), and Nothin' But Love (2000).

Booker's only outing as a leader in his own right, Bookie's Cookbook, was recorded in 1999 and released in 2000 on Mapleshade Records, fronting a quintet with Cecil Payne on baritone saxophone, Marcus Belgrave on trumpet, guitarist Roni Ben-Hur, pianist Larry Willis, and drummer Leroy Williams; Booker composed the track "Pete's Rock." The following year he was the bassist on Ben-Hur's Anna's Dance (2001, Reservoir), alongside pianist Barry Harris, drummer Leroy Williams, and tenor saxophonist Charles Davis. He kept performing into his final years, with his last documented performances in December 2004. Walter Booker died of cardiac arrest at his home in Manhattan on November 24, 2006, at age 72, after being treated for prostate cancer; he was survived by his wife, Bertha Hope-Booker, three sons, three stepchildren, a sister, and grandchildren.

Booker was never a flashy soloist, and critics and colleagues alike described him instead as a reliable, steady-handed stylist with an unusually big tone and real command of the bass's higher register, qualities that made him equally at home anchoring the hard-swinging, soul-jazz-inflected book of Cannonball Adderley's quintet and the more open, postbop small groups he favored later with pianist John Hicks and his wife, pianist Bertha Hope. His willingness to step outside the bass chair entirely, playing classical guitar on Wayne Shorter's Super Nova, points to a broader musicianship than his catalog of straight-ahead sideman dates alone suggests. As a bandleader in his own right he surfaced only once, on 2000's Bookie's Cookbook, but as an in-demand session and touring bassist across five decades he was a constant presence on other people's records, prized for exactly the consistency and "congruity to other players" that made him, in his own words to interviewers, most comfortable inside someone else's music.