Leroy Vinnegar was born July 13, 1928, in Indianapolis, Indiana, and never took a formal music lesson. He started on piano in 1945 and moved to the bass in 1948, after a bandmate left an instrument at his house and he discovered how short his hometown was of players who could handle it. The Indianapolis dance halls of his teens brought touring orchestras through town, including Duke Ellington's and Count Basie's, and he came up in the same local scene that produced guitarist Wes Montgomery. Everything he knew about the instrument he worked out by ear, on the bandstand.

In 1952 he moved to Chicago and landed in the house rhythm sections that backed visiting soloists at clubs including the Bee Hive and the Blue Note. Over the next two years he played behind Charlie Parker, Sonny Stitt, Lester Young, Howard McGhee, Johnny Griffin, and Miles Davis, absorbing bebop's vocabulary directly from the people who had built it. Parker gave him advice he repeated for the rest of his life: listen to what is going on around you, and let the melody dictate the changes. It was also in this period that Vinnegar, who could not yet read music, was taught to do so by bassists Red Callender and Joe Comfort. That skill would matter enormously once he reached the West Coast studios.

Vinnegar relocated to Los Angeles in 1954 on an invitation to join Art Tatum's trio, and within a year or two he was the city's first-call bassist. He became the effective house bassist for Lester Koenig's Contemporary Records, and on August 17, 1956, in a single evening session at the Contemporary studio, he cut the record that made him famous: Modern Jazz Performances of Songs from My Fair Lady, billed to Shelly Manne & His Friends with pianist Andre Previn. It was the first jazz album built entirely from one Broadway score, an instant hit, and for a time the best-selling jazz record ever made. Manne and Previn kept the format going for years afterward with Li'l Abner, Pal Joey, Gigi, and West Side Story, but by then Red Mitchell had taken over the bass chair, Vinnegar having moved on to other work.

That other work was constant. Between 1955 and 1965 he appeared on a large share of the significant records made in Los Angeles: Stan Getz's West Coast Jazz (Norgran, 1955) and Hamp and Getz with Lionel Hampton the same year, Serge Chaloff's Blue Serge (recorded at Capitol's Hollywood studio on March 14 and 16, 1956, and still regarded as Chaloff's finest hour), dates with Chet Baker, Lee Konitz, Shorty Rogers, Dexter Gordon, Art Pepper, Benny Carter, Barney Kessel, Harold Land, and a long run of albums with tenor saxophonist Teddy Edwards. In July 1957 in Hollywood he played bass on the Pepper Adams Quintet date for Mode Records, Pepper Adams's recorded debut as a leader, alongside trumpeter Stu Williamson, pianist Carl Perkins (like Vinnegar, an Indianapolis native born in 1928), and drummer Mel Lewis. In October 1958 he was in the rhythm section for Sonny Rollins and the Contemporary Leaders. He also worked the Lighthouse Café in Hermosa Beach through the late 1950s. His own leader career started in the same stretch: Leroy Walks! (Contemporary, recorded July and September 1957, released 1958), Leroy Walks Again!! (recorded 1962 and 1963), and Jazz's Great "Walker" for Vee Jay in 1964.

Through the 1960s and 1970s Vinnegar split his time between jazz, studio dates, and film and television sessions, the last of these largely to support his family. He was the bassist in Les McCann's trio for years, a partnership that produced Les McCann Ltd. Plays the Truth (1960) and, most consequentially, Swiss Movement, recorded live at the Montreux Jazz Festival on June 21, 1969 with saxophonist Eddie Harris and trumpeter Benny Bailey. It went to number one on Billboard's jazz chart, number two R&B, and number 29 on the pop LP chart, drew a Grammy nomination, and sold in the millions on the strength of "Compared to What." His own composition "Kaftan" was added as a bonus track on the album's 1996 reissue. Pop and rock producers found him too: he played acoustic bass on "Spanish Caravan" from The Doors' Waiting for the Sun (1968), on "Almost Independence Day" from Van Morrison's Saint Dominic's Preview (1972), and on Jimmy Smith's Bluesmith (1972). He led two funk-inflected dates of his own in this period, Glass of Water (Legend, 1973) and The Kid (PBR International, 1974), and in 1980 he traveled to Senegal with Al Cohn, Billy Mitchell, Dolo Coker, and Frank Butler for the Xanadu sessions released as Night Flight to Dakar and Xanadu in Africa.

Vinnegar began visiting Portland, Oregon, in 1973 and moved there permanently in 1986, partly to ease the heart and lung disease that would eventually keep him on supplemental oxygen fifteen hours a day. He became a fixture of the local scene, playing Portland rooms including Berbati's and Atwater's, teaching at Portland State University, and mentoring younger Northwest players while holding the bebop line against fusion. He recorded Walkin' the Basses in Milwaukie, Oregon, in March 1992 (released on Contemporary in 1993), then Encounters (1994) and Encounters II (1997) with pianist Jessica Williams and drummer Mel Brown for the Jazz Focus label, and Integrity in 1998. In 1995 the Oregon legislature designated May 1 as Leroy Vinnegar Day; in 1998 he became the first inductee into the Jazz Society of Oregon's Hall of Fame. He suffered a fatal heart attack in a Portland hospital on August 3, 1999, at 71. Portland State University's jazz program is now the Leroy Vinnegar Jazz Institute, and his papers and recordings are held there.

Vinnegar's whole reputation rests on one thing done better than almost anyone: the walking bass line, a steady four-to-the-bar procession of quarter notes climbing and descending through the harmony, which earned him the nickname "The Walker" and, on Leroy Walks!, an album whose every track title contains the word. He was not a soloist's bassist in the manner of Ray Brown or Red Mitchell, both of whom pushed the instrument toward melodic display; his gift was a huge, woody, unhurried tone and a sense of time so anchored that leaders hired him specifically to make a rhythm section stop wobbling. He described his own method as keeping the pulse dead center while finding a different line every eight bars, and that combination of reliability and invention is why Lester Koenig used him as Contemporary's default bassist and why Andre Previn and Shelly Manne called him a full "third voice" rather than an accompanist on My Fair Lady. He wrote as well as walked, contributing "Walk On," "Hard to Find," "Subway Grate," "Kaftan," and "For Carl," the last an elegy for the pianist Carl Perkins, who had played on Leroy Walks! and died in 1958 at 29. Critics have treated his leader dates as solid rather than revolutionary, with The Penguin Guide to Jazz Recordings giving Leroy Walks! three and a half stars out of four and Scott Yanow reading Leroy Walks Again!! as a snapshot of the moment cool jazz gave way to hard bop, but his standing as a sideman is not in dispute: he is on two of the best-selling jazz albums ever released.