Samuel Carthorne Rivers was born September 25, 1923, in El Reno, Oklahoma. His father was a gospel musician who had sung with the Fisk Jubilee Singers and the Silverstone Quartet, and his grandfather, Marshall W. Taylor, was a religious leader from Kentucky, so Rivers grew up around music from childhood. He served in the Navy in the 1940s, stationed in California, where he performed semi-regularly with the blues singer Jimmy Witherspoon. In 1947 he moved to Boston, Massachusetts, and studied at the Boston Conservatory under the composer Alan Hovhaness, working locally with Quincy Jones, Herb Pomeroy, and Tadd Dameron as he built a reputation in the city's bebop scene.

In 1959 Rivers began performing with a 13-year-old drummer named Tony Williams, a relationship that would change the direction of his career. On Williams's recommendation, Rivers joined the Miles Davis Quintet in 1964, appearing on the single live album the group produced, Miles in Tokyo, recorded July 14 at Kohseinenkin Hall with Davis, Ron Carter, Tony Williams, and Herbie Hancock. The stint was brief: his playing was already pushing further outside the harmony than Davis wanted at the time, and he was replaced within months by Wayne Shorter. Blue Note Records signed him that same year. Over the rest of the decade he recorded four albums as a leader for the label: Fuchsia Swing Song (1965), with Jaki Byard, Ron Carter, and Tony Williams; Contours (1967), with Freddie Hubbard, Herbie Hancock, Ron Carter, and Joe Chambers; A New Conception (1967), a standards-based quartet date with Hal Galper, Herbie Lewis, and Steve Ellington; and Dimensions & Extensions (recorded 1967, not released until 1986), with Donald Byrd, Julian Priester, James Spaulding, and Cecil McBee. He also appeared as a sideman on other Blue Note sessions of the period, including Tony Williams's Life Time (1964) and Spring (1966), Larry Young's Into Somethin' (1965), Bobby Hutcherson's Dialogue (1965), and Andrew Hill's Change (recorded 1966). His ballad "Beatrice," from Fuchsia Swing Song, went on to become a standard among tenor saxophonists, later recorded by Joe Henderson on The State of the Tenor and by Stan Getz.

Through the 1970s Rivers and his wife, Beatrice, ran Studio Rivbea, a jazz loft on Bond Street in Manhattan's NoHo district, opened in 1970 as part of the first New York Musicians Festival. The critic John Litweiler later wrote that "in New York, loft jazz meant free jazz in the seventies," calling Studio Rivbea the movement's most famous venue; a series of recordings made there was issued as the Wildflowers sessions on the Douglas label. Rivers continued to record through the decade, including several albums for Impulse!: Streams, recorded live at the Montreux Jazz Festival, the trio sessions later collected on Hues, the quartet date Sizzle, and his first big-band record, Crystals. The best-known recording of the period, though, is one on which he was a sideman rather than a leader: Dave Holland's Conference of the Birds (1973, ECM), the only occasion Rivers and Anthony Braxton, two of the era's most original saxophonists, recorded together, alongside Holland and drummer Barry Altschul. Rivers and Holland's musical partnership continued afterward on Rivers's own Sizzle and Contrasts (1980, ECM, with trombonist George Lewis), and much later on the trio reunion album Reunion: Live in New York (recorded 2007).

In the early 1990s Rivers and Beatrice moved to Orlando, Florida, in part so he could develop his orchestral writing with a dedicated reading band; the resulting group became the longest-running edition of the RivBea Orchestra, and he also led a working trio there with bassist Doug Mathews and drummer Anthony Cole. Between 1996 and 1998 he recorded three projects in France for Nato Records with pianist Tony Hymas. In 1998, with help from the saxophonist and producer Steve Coleman, he recorded two big-band albums for RCA Victor with the RivBea All-Star Orchestra, Culmination and Inspiration, both of which received Grammy nominations; the title track of Inspiration is an elaborate reworking of Dizzy Gillespie's "Tanga," a nod to Rivers's own late-career stint in Gillespie's band. He kept recording into his eighties, releasing Celebration in 2004 and the three-disc Mosaic Records box Trilogy in 2011, the year of his death. Rivers died of pneumonia on December 26, 2011, in Orlando, at the age of 88. Between 2019 and 2022, NoBusiness Records issued six further live albums drawn from his personal tape collection as the Sam Rivers Archive Series, and "Beatrice" itself keeps circulating well beyond jazz circles, most recently as the tune Israeli saxophonist Yuval Cohen covered on his own 2007 debut, Freedom.

Rivers's playing grew out of bebop but pushed past it: his approach, sometimes called "inside-outside," frequently abandons the stated harmony to play "outside" it while keeping a concealed thread back to the changes, so that a solo can return to the form without ever sounding like it left carelessly. He was unusually versatile for a saxophonist of his generation, moving between tenor and soprano saxophone, bass clarinet, flute, and piano within a single set or record, and his writing for larger ensembles, from Crystals through the Grammy-nominated RivBea All-Star Orchestra albums, extended that same harmonic freedom to big-band composition. As a bandleader and loft-scene organizer at Studio Rivbea he was a central, hands-on figure in 1970s free jazz, providing a stage and a model of artist-run presentation for a generation of players who came after him. "Beatrice," his best-known composition, has had a life independent of his own catalog, covered by tenor players from Joe Henderson to Stan Getz to Yuval Cohen decades later.