Sidney Joseph Bechet was born on May 14, 1897, in New Orleans, into a middle-class Creole of color family. His father, Omar, was a shoemaker and flute player, and his older brother Leonard was a dentist who played trombone and led a band on the side. Bechet taught himself on the instruments kept around the house, starting on cornet and settling on clarinet, and at six he played with his brother's band at a family birthday party. His early teachers and colleagues included the clarinetists Lorenzo Tio, "Big Eye" Louis Nelson Delisle and George Baquet, and he worked with Freddie Keppard's brass band, with Bunk Johnson in the Eagle Band in 1911 and 1912, and with King Oliver in the Olympia Band in 1913 and 1914. From 1914 to 1917 he traveled, going as far north as Chicago.

In the spring of 1919 he went to New York and joined Will Marion Cook's Syncopated Orchestra, which sailed for Europe and played London's Royal Philharmonic Hall. Bechet was a favorite with the audiences, and in London he came across a straight soprano saxophone, the instrument that became his main voice. The Swiss conductor Ernest Ansermet wrote a tribute to him that year, among the earliest essays on a jazz musician by a classically trained authority, and it linked his playing with Bach. Back in the United States he made his first records on July 30, 1923, "Wild Cat Blues" and "Kansas City Man Blues," with pianist Clarence Williams's Blue Five, a few months after Louis Armstrong made his own recording debut with King Oliver. Armstrong joined the Blue Five the following year, and the two recorded together again later that year and in January 1925, including "Cake Walkin' Babies from Home" under the Red Onion Jazz Babies name. In 1924 Bechet also spent about three months with Duke Ellington's band, where Sonny Greer felt he fit the group perfectly; his habit of missing work, including a stretch of three days in a row, ended the stay, though Ellington later called him the epitome of jazz.

On September 15, 1925, Bechet sailed for France with the Revue Nègre, the show built around Josephine Baker, which opened at the Théâtre des Champs-Élysées in Paris on October 2. He toured Europe with several bands, reaching Russia in mid-1926, and in 1928 led a small band at Bricktop's club in Montmartre. That same year a quarrel with another musician ended in gunfire that wounded bystanders; he spent eleven months in a Paris prison and was then deported to the United States. Back in New York he worked on and off from 1931 with Noble Sissle's orchestra, which kept him recording through the thin years, and in 1932 he formed the New Orleans Feetwarmers with trumpeter Tommy Ladnier, a band that made a celebrated Victor session on September 15, 1932. Work was scarce enough that Bechet and Ladnier ran a tailor shop where musicians jammed in the back. Both men appeared in John Hammond's first From Spirituals to Swing concert at Carnegie Hall in December 1938, and sessions Mezz Mezzrow organized for the French critic Hugues Panassié that November helped start the New Orleans revival.

Recognition began to return in 1939. "Summertime," which Bechet could not place with the established record companies, became the first hit for the young Blue Note label, and the 1939 recording entered the Grammy Hall of Fame in 2011. The same year he and pianist Willie "The Lion" Smith led a group that cut early versions of what was later called Latin jazz, adapting méringue, rhumba and Haitian songs. In 1938 his guitarist Leonard Ware and two session singers wrote "Hold Tight (Want Some Seafood Mama)," with contributions claimed by Bechet, and its suggestive lyrics and the lawsuits over royalties kept it in the news; Fats Waller recorded it for Victor in January 1939. Bechet then signed with Victor's Bluebird line, recorded with the Feetwarmers through 1941, and on April 18, 1941, made "The Sheik of Araby" alone, overdubbing clarinet, soprano and tenor saxophones, piano, bass and drums in an early experiment with the technique.

Through the 1940s he worked in New York, played on some of Eddie Condon's Town Hall concerts, shared a September 1946 Town Hall stage with pianist James P. Johnson, who made his last preserved appearance with a Bechet group in March 1950, took part in the sessions Mezzrow recorded for his King Jazz label, and began teaching a teenage Bob Wilber in 1945. A planned band with the veteran trumpeter Bunk Johnson fell apart in 1945 when Johnson's drinking got in the way. Bechet's contract with the Chicago label Jazz Limited kept him off the 1948 jazz festival in Nice, and he sent Wilber in his place. Paris gave him the welcome the United States had not: his Salle Pleyel appearance at the Paris jazz festival in 1949 caused a sensation, and in 1951 he moved to France for good. He married Elisabeth Ziegler in Antibes that year, signed with Disques Vogue in 1953 on a contract that ran for the rest of his life, and recorded a string of French hits, among them "Les Oignons," "Promenade aux Champs-Élysées" and "Petite Fleur." He worked with the orchestras of Claude Luter and André Réwéliotty, wrote a late-Romantic ballet score, "La nuit est une sorcière" ("The Night Is a Witch"), appeared in three French films, and was nicknamed le dieu by some of the Paris existentialists. In 1958 he was a soloist at the Brussels World's Fair, in concerts that also featured trumpeter Buck Clayton and Sarah Vaughan.

Shortly before his death he told his story in the autobiography Treat It Gentle (1960), a colorful, embellished and often inaccurate account that remains a standard insider's view of New Orleans music. Bechet passed away of lung cancer on May 14, 1959, his 62nd birthday, in Garches, near Paris, and is buried in the local cemetery. He entered the Down Beat Hall of Fame in 1968 and the Big Band and Jazz Hall of Fame in 1983, a blue plaque marks his former London home, and a crater on Mercury and a park in Antibes bear his name.

Bechet was one of the first important soloists in jazz and the first influential soprano saxophonist. He played with a broad, quick vibrato, a big, emotionally charged sound and a lead player's authority, and he was so dominant that trumpeters found it hard to share a front line with him; as a rule it was up to the other horns to stay out of his way. His clarinet and soprano style changed little over his career, but he never lost his drive, and he was as strong in collective improvisation as in extended solos. Like Coleman Hawkins, he had a reputation for an abrasive, impatient manner with younger players, and he never learned to read music. Ansermet's 1919 essay tied his playing to the classical tradition, and the French public later made him a national favorite. His example runs through the revival of early jazz: his pupil Bob Wilber founded a Bechet Legacy band, Steve Lacy built his soprano language on a Bechet-derived vocabulary learned in Dixieland bands, Archie Shepp recorded a tribute to him, Aldo Romano made Because Of Bechet (2002) with a group that included saxophonists Emanuele Cisi and Francesco Bearzatti, and Evan Christopher devoted Blues in Air: The Music of Sidney Bechet (2022) to his music.