Chesney Henry "Chet" Baker Jr. was born December 23, 1929, in Yale, Oklahoma, to Chesney Baker Sr., a professional Western swing guitarist, and Vera Moser, a pianist who worked in a perfume factory. The Great Depression pushed his father out of music and into regular work, and in 1940 the family relocated to Glendale, California. Baker sang in his church choir before taking up trombone at his father's suggestion; at thirteen, finding the trombone too large, he switched to trumpet and progressed quickly. He left Glendale High School at sixteen and joined the United States Army in 1946, landing in Berlin with the 298th Army Band, where he first encountered modern jazz through V-Discs of Dizzy Gillespie and Stan Kenton. After his 1948 discharge he studied briefly at El Camino College before re-enlisting and joining the Sixth Army Band at San Francisco's Presidio, gigging at clubs like Bop City and the Black Hawk. He left the Army for good in 1951.

Baker's break came almost immediately. He worked with Vido Musso and Stan Getz before Charlie Parker himself picked the young, largely self-taught trumpeter for a series of 1952 West Coast engagements. That same year Baker joined baritone saxophonist Gerry Mulligan's pianoless quartet, a group built on close, spontaneous counterpoint rather than the harmonic density of East Coast bebop. The pairing was an immediate sensation: Baker and Mulligan traded and anticipated each other's lines in a way no rhythm-section-less horn group had before, and Baker's solo on "My Funny Valentine" became a signature so enduring that a 1953 quartet recording of the tune was inducted into the Library of Congress's National Recording Registry in 2015. In 1954, Baker topped both the Metronome and DownBeat readers' polls for trumpet, ahead of Miles Davis and Clifford Brown, and was named the year's top jazz vocalist as well — a reflection of how fast his profile had grown beyond the Mulligan association, playing regularly at Los Angeles rooms like The Haig with his own group.

Pacific Jazz released Chet Baker Sings in 1954, over the doubts of producer Dick Bock, who wasn't sure a trumpet star should also be presented as a singer. The album's hushed, unschooled vocal delivery on standards like "But Not for Me" and "My Funny Valentine" turned out to be exactly what widened his audience past the jazz-only crowd. Between his boyish, William Claxton-photographed looks and his measured, unbothered stage presence, Baker became something close to a matinee idol — jazz historian Dave Gelly's line that he embodied "James Dean, Sinatra, and Bix, rolled into one" captures the moment. Hollywood noticed too: Baker made his film debut in Hell's Horizon (1955) but turned down a studio contract to stay on the road. In September 1955 he left for an eight-month European tour, recording for the Barclay label in Paris that October. A month in, pianist Dick Twardzik — the young player who'd brought composer Bob Zieff's tunes into Baker's book — died of a heroin overdose; Baker finished the tour with local replacements. The Paris sessions were later issued in the U.S. as Chet Baker in Europe.

Back in Los Angeles, Baker cut further Pacific Jazz sides, including Chet Baker & Crew and, with Art Pepper, Playboys (its cover, a near-parody of Playboy magazine's wordmark and pinup style, reportedly drew a legal threat from Hugh Hefner). He then moved to New York, reuniting briefly with Mulligan for December 1957 sessions issued as Reunion with Chet Baker, rejoining Stan Getz for Stan Meets Chet in 1958, and signing to Riverside for (Chet Baker Sings) It Could Happen to You, Chet Baker in New York, and 1959's instrumental Chet — the latter notable for pairing him with pianist Bill Evans, bassist Paul Chambers, and drummer Philly Joe Jones, all closely associated with Miles Davis's bands of the period. Baker later dated the start of his heroin use to 1957, though his biographer Jeroen de Valk and pianist Russ Freeman both place it earlier, in the early 1950s. Soon after the Riverside signing he was arrested twice, spending time at a Lexington, Kentucky treatment hospital and four months at Rikers Island on drug charges.

The addiction followed him to Europe. Recording in Italy in late 1959 and through 1960 (the "Milano sessions," with arranger Ezio Leoni), Baker drew tabloid attacks over his drug use and personal life, and in August 1960 was imprisoned in Lucca for importing narcotics and forging prescriptions — nearly a year and a half behind bars. Further arrests and deportations moved him through West Germany, Switzerland, France, and England before he was sent back to the United States. His first post-Italy release, 1962's Chet Is Back!, was recorded in Rome for RCA with a sextet of rising European players (Bobby Jaspar, René Thomas, Amedeo Tommasi) and, unusually, paired with orchestral pop sessions he cut around the same time with the young composer Ennio Morricone.

The 1960s wore Baker down. He recorded prolifically but unevenly — five albums for Prestige inside a single week in 1964, Baby Breeze for Limelight in 1965, and a run of Pacific releases he later dismissed as work done strictly to pay the rent for his wife and three children. In summer 1966, after a gig in Sausalito, he was beaten while reportedly attempting to buy drugs, sustaining cuts and several broken teeth; by the end of the decade he needed dentures, which effectively destroyed his embouchure. It took years of relearning to get his trumpet playing back, and from 1968 to 1973 he largely disappeared from public performance, living at his mother's San Jose home, on welfare, arrested at one point for forging heroin prescriptions and placed on a seven-year methadone order by a judge.

Baker's comeback began in 1973. Driving to New York to work his way back into straight-ahead jazz, he cut a 1974 live album with Lee Konitz and, that same year, the CTI session She Was Too Good to Me — his acknowledged comeback record, arranged by Don Sebesky with strings and a cast including Ron Carter, Hubert Laws, and Paul Desmond. In November 1974 he and Mulligan reunited one final time on record for a Carnegie Hall concert (released as a CTI double LP the following year) with a young guitarist named John Scofield in the band — the beginning of a working relationship Baker and Scofield would continue on 1977's You Can't Go Home Again, before Scofield's own career took off with Miles Davis and as a leader. Baker also cut Once Upon a Summertime in 1977. That November he toured Europe and, meeting renewed demand in France, Italy, Germany, and Denmark that the U.S. scene no longer offered him, chose to stay.

From 1977 until his death, Baker worked almost exclusively in Europe, returning to the States about once a year. The pace of his recording became extraordinary — by his biographers' count, eleven albums in 1979 alone and ten more in 1980 — for small European jazz labels including Circle, SteepleChase, and Enja. He gravitated toward a regular circle of European collaborators: guitarist Philip Catherine, bassist Niels-Henning Ørsted Pedersen, pianist Michel Graillier, and later pianist Paul Bley, with whom he recorded the 1985 duo album Diane. He increasingly preferred small, drummerless settings, put off by loud rooms and inattentive audiences. In 1983, Elvis Costello — a longtime admirer — brought him in to play the trumpet solo on "Shipbuilding," introducing Baker to a new, non-jazz audience; Baker began closing sets with Costello's "Almost Blue" in return. A 1985 trip to Rio de Janeiro's Free Jazz Festival led to a duet album with Brazilian pianist Rique Pantoja, and in 1986 he appeared alongside Costello and Van Morrison in the concert film Chet Baker: Live at Ronnie Scott's London, speaking candidly on camera about his addiction and his childhood. His 1987 quartet date with pianist Harold Danko, bassist Hein Van de Geyn, and drummer John Engels, released as Chet Baker in Tokyo, appeared eleven months before his death and was singled out by critic John Vinocur as one of the finest recordings of his late period.

In winter 1986, fashion photographer Bruce Weber met Baker at a New York club and proposed a short film; by the time shooting began in January 1987 it had grown into the feature-length documentary Let's Get Lost, which set Baker's youthful glamour against his ravaged later appearance and earned an Academy Award nomination. It was released in September 1988, four months after Baker didn't live to see it in theaters. Early on May 13, 1988, he was found dead on the street below his room at Amsterdam's Hotel Prins Hendrik, having fallen from a window with no sign of a struggle; heroin and cocaine were found in his system. Dutch police called it an accident, likely drug-related, though the ambiguity of the scene left the question open, and Baker's widow was among those who suspected he had been pushed. He is buried at Inglewood Park Cemetery in Inglewood, California, next to his father.

Baker's playing was the defining instrumental voice of West Coast cool: a light, vibrato-light tone, phrases built around melodic economy rather than harmonic density, and a preference for space and restraint over the volume and speed then dominating East Coast hard bop. He was largely self-taught and played by ear rather than by rigorous theory, which contributed to a sound critics described as intuitive and unguarded rather than virtuosic — closer to a singer's phrasing than a technician's. That carried directly into his vocal work: on Chet Baker Sings and after, he sang in a hushed, almost breathy near-whisper with none of the theatrical projection of contemporary jazz vocalists, an approach some critics found affecting and others found thin, but which became as recognizable as his horn. The 1966 beating and its damage to his embouchure forced a harder-won, more weathered tone in his later trumpet playing — still lyrical, but with an audibly different, more fragile edge that many listeners came to prize in its own right. In his final decade in Europe, Baker leaned increasingly toward small, often drummerless combinations built around close listening, working repeatedly with players like Philip Catherine and Paul Bley in settings that let his tone, rather than the rhythm section, set the terms of a performance.