Robert Henry Timmons was born in Philadelphia on December 19, 1935, the son of a minister. Both parents and several aunts and uncles played piano, and his first public performances were at his grandfather's church. His formal teacher was his uncle, Robert Habershaw, who also taught McCoy Tyner. He grew up in the same North Philadelphia circle as the Heath brothers and Lee Morgan, and after high school won a scholarship to the Philadelphia Musical Academy. He moved to New York in 1954, and his recording debut came on May 31, 1956, when Kenny Dorham took a sextet into the Café Bohemia for 'Round About Midnight at the Café Bohemia (Blue Note BLP 1524) with Kenny Burrell on guitar and Sam Jones on bass. Work with Chet Baker followed in 1956 and 1957, then Sonny Stitt in 1957 and Maynard Ferguson in 1957 and 1958. Blue Note began calling: he is the pianist on Curtis Fuller's The Opener, cut June 16, 1957, and on Lee Morgan's The Cooker, recorded September 29, 1957 with Pepper Adams on baritone saxophone.

Benny Golson recruited Timmons into Art Blakey's Jazz Messengers in July 1958, and he stayed until September 1959. On October 30, 1958, at Rudy Van Gelder's studio in Hackensack, the quintet of Blakey, Lee Morgan, Golson, Timmons and bassist Jymie Merritt recorded the album that made him. It was issued as Art Blakey and the Jazz Messengers (Blue Note BLP 4003) and only later retitled Moanin' after its opening track, Timmons's own. Golson's account of the tune's origin is the one that has stuck: Timmons had been playing the eight-bar call-and-response figure between numbers, and Golson pushed him to write a bridge and finish it. Timmons was 22. The recording entered the Grammy Hall of Fame in 1998 and the album followed in 2001. The same band, with Hank Mobley in Golson's chair, was taped live at Birdland on April 15, 1959 for At the Jazz Corner of the World Vols. 1 and 2.

In October 1959 Timmons left for the Cannonball Adderley Quintet. On October 18 and 20 he was at the Jazz Workshop in San Francisco for The Cannonball Adderley Quintet in San Francisco, with Nat Adderley, Sam Jones and Louis Hayes. The album opens with a 12-minute reading of Timmons's "This Here," and it sold roughly 50,000 copies by May 1960, a figure Time called extraordinary for a jazz record. The February 1, 1960 New York session for Them Dirty Blues introduced a second Timmons original, "Dat Dere," to which Oscar Brown Jr. added lyrics later that year. In between, Riverside gave Timmons his own contract: This Here Is Bobby Timmons was recorded January 13 and 14, 1960 at Reeves Sound Studios with Sam Jones and Jimmy Cobb, and its nine tracks include his own readings of "This Here," "Moanin'" and "Dat Dere."

Dissatisfied with what "This Here" was actually earning him, Timmons went back to Blakey in February 1960 for better money and stayed until June 1961. That second stint produced the front line of Lee Morgan and Wayne Shorter: The Big Beat (recorded March 6, 1960), A Night in Tunisia (August 7 and 14, 1960), Meet You at the Jazz Corner of the World Vols. 1 and 2 (live at Birdland, September 14, 1960), The Witch Doctor (March 14, 1961, shelved until 1967) and The Freedom Rider (February 18 and May 27, 1961, issued in 1964).

He left the Messengers in June 1961 to lead his own trio, first with Ron Carter and drummer Albert "Tootie" Heath, the group documented live at the Village Vanguard on October 1, 1961 for In Person. He worked mainly around New York for the rest of his life. Riverside kept him through Born to Be Blue! in 1963; Prestige took him from 1964 to 1966 for seven albums including a Christmas record, and Milestone issued the ambitious Tom McIntosh-arranged nonet date Got to Get It! in 1968. He picked up the vibraphone in the mid-1960s and played it on Chicken & Dumplin's, and on the 1964 session issued as From the Bottom he is credited on piano, organ and vibraharp. Heroin addiction dating from the late 1950s and, later, heavy drinking narrowed his career, as did being typecast as the funky-tune writer. In early 1974 he joined Clark Terry's big band for a European tour, drank heavily on the flight to Sweden and collapsed at a bar before the first Malmö concert. He was flown home and spent a month in hospital. Bobby Timmons passed away at St. Vincent's Hospital in New York on March 1, 1974, of cirrhosis, at 38. He was buried in Philadelphia, survived by his wife Estelle and son Bobby Jr.

Timmons built his sound on block chords, the right hand carrying the melody while the left moves in the same rhythm without reharmonizing, and he attacked them harder and with less decoration than Red Garland, whose trios along with Ahmad Jamal's shaped his own group concept. Underneath sat Bud Powell, whom Ron Carter named as the primary influence, and above it the church: the gospel cadences he had grown up playing turned a bebop pianist into the definitive soul jazz stylist almost by accident. Timmons himself was dismissive of his composing, calling himself a dilettante who never sat down deliberately to write a song, yet "Moanin'," "This Here" and "Dat Dere" between them did as much as any three tunes to establish the gospel-inflected soul jazz of 1959 to 1962, and his playing fed directly into Les McCann, Ramsey Lewis and, a generation later, Benny Green. The Penguin Guide to Jazz characterizes his style as rolling gospel funk with more energy than harmonic subtlety, a fair description of the hits and an unfair one of the ballads: Gary Giddins singled out his Powell-derived long lines and his refusal to sentimentalize slow tempos. Marc Myers wrote in 2008 that his contribution as accompanist, writer and bandleader remains badly undervalued, and the imbalance is visible in the numbers, since Discogs lists 1,379 releases carrying his name and only 52 of them are his own.