Ronald Albert Mathews was born December 2, 1935, in New York City. He studied piano, theory, and composition at Brooklyn College and the Manhattan School of Music, earning his B.M. in 1959. He made his first appearance on record as a sideman on tenor saxophonist Roland Alexander's Pleasure Bent (recorded June 17, 1961, New Jazz), and his first date as a billed leader came two and a half years later: Doin' The Thang! (recorded December 17, 1963, Van Gelder Studio, Englewood Cliffs, released 1964 on Prestige), co-billed with Freddie Hubbard and featuring Charles Davis on baritone saxophone. Prestige later paired both sessions on a single 2002 CD reissue.

Through the rest of the 1960s Mathews built a career as one of New York's most reliable hard-bop sidemen. He toured and recorded internationally with Max Roach between 1963 and 1968, appearing on Roach's Drums Unlimited (Atlantic, recorded 1965 and released 1966), and worked the same period with Freddie Hubbard and Roy Haynes. His association with Haynes produced two 1963 Van Gelder sessions for the Roy Haynes Quintet with Booker Ervin, Cracklin' (recorded April 10, 1963) and Cymbalism (recorded September 10, 1963), both released on New Jazz, with Mathews also credited as a co-writer on several tracks. He joined Art Blakey's Jazz Messengers for stretches in 1967-69 and again in 1975, touring Europe and Japan; a Messengers live date at Slug's Saloon in New York in August 1968, with Bill Hardman, Julian Priester, and Billy Harper in the front line, was later issued as Live! Vol. 1 (Trip Records, 1974) and again, repackaged with the same performance, as Moanin' (Sarpe/Valentine, 1990).

The 1970s brought Mathews into two overlapping working bands built around trumpeter Woody Shaw: the Louis Hayes-Junior Cook Quintet and, when Shaw stepped to the front, the Louis Hayes-Woody Shaw Quintet, documented on Ichi-Ban (recorded May 5, 1976, Generation Sound Studio, NYC, Timeless) and the live At the Berliner Jazztage (recorded November 6, 1976 at the Berlin Jazz Festival, Muse), the latter with Frank Foster, Rene McLean, and Slide Hampton. He also began recording as a leader in his own right for the first time since 1964: Trip to the Orient (recorded July 1975 at Vanguard Studio, NYC, released on the Japanese East Wind label with bassist Yoshio Suzuki and Louis Hayes), followed by two dates for the Chicago label Bee Hive, Roots, Branches & Dances (recorded December 7, 1978, with Frank Foster and Al Foster) and Legacy (recorded September 21, 1979, with Bill Hardman, Ricky Ford, Walter Booker, and Jimmy Cobb).

From 1978 to 1982 Mathews held the piano chair in the Johnny Griffin Quartet, appearing on Griffin's Return of the Griffin, NYC Underground, and To the Ladies, among others; The New York Times called him "a constant and provocative challenge" to Griffin on the bandstand. He kept up a steady run of trio leader dates through the 1980s and 1990s: Song for Leslie (recorded March 1, 1980, in Bologna, Italy, with Ray Drummond and Kenny Washington), So Sorry Please... (1985, Nilva), Selena's Dance (recorded February 1, 1988, in the Netherlands, with Stafford James and Tony Reedus), Dark Before the Dawn (recorded October 26, 1990, with Ray Drummond and Billy Higgins), At Cafe des Copains (1992, Sackville, a solo piano recording with no other musicians credited, in keeping with the Toronto club's long-running solo piano series), Lament for Love (recorded June 9, 1992, with David Williams and Frank Gant), and Shades of Monk (recorded May 16-17, 1994, an all-Thelonious Monk program with Buster Williams and Kenny Washington). He was also a member of the Clifford Jordan Big Band in the early 1990s and spent eight years touring and recording with T.S. Monk's band. By his early thirties he had begun teaching jazz piano and leading workshops and master classes at Long Island University, work he continued for the rest of his career.

Mathews's later credits ranged widely: he was the pianist for the Tony Award-winning Broadway musical Black and Blue in 1989, recorded for the soundtrack of Spike Lee's Mo' Better Blues in 1990, and published a student arrangement collection, Easy Piano of Thelonious Monk (Hal Leonard, 1998). His last trio album, Once I Love (recorded May 20-21, 2001, in Sapporo, Japan, with Walter Booker and Alvin Queen), appeared on the Japanese Sound Hills label in 2002. Later that decade he recorded twice with guitarist Roni Ben-Hur: Keepin' It Open (2007), alongside Lewis Nash and Jeremy Pelt, and Fortuna (2009), his final commercially released recording, alongside Nash and Rufus Reid. In 2008 he also served as mentor and pianist on Generations, led by drummer Jimmy Cobb, contributing two original compositions. Ronnie Mathews passed away on June 28, 2008, in Brooklyn, of pancreatic cancer, at age 72.

Mathews played a percussive, harmonically dense hard bop rooted in bebop's vocabulary, and critics repeatedly placed him in the company of Thelonious Monk, Bud Powell, and McCoy Tyner, not as an imitator of any of them but as a pianist working the same terrain with his own touch. He was a first-call accompanist precisely because that vocabulary held up in almost any context: bebop-era tenor and trumpet frontlines, Woody Shaw's more modally adventurous bands, Johnny Griffin's combative quartet, and later straight-ahead trio settings built entirely around his own compositions and arrangements. Despite four decades of steady, well-documented work, he remained, in the assessment of several jazz historians, one of the era's most under-recognized pianists relative to his actual contribution.