A pioneer in the development of bebop and its associated contributions to jazz theory,[2] Powell's application of complex phrasing to the piano influenced both his contemporaries and later pianists including Walter Davis Jr., Toshiko Akiyoshi, and Barry Harris.

A severe beating by police in 1945 and years of electroconvulsive therapy treatments adversely impacted his mental health, but his recordings and live performances with Charlie Parker, Sonny Stitt, and Max Roach during the late 1940s and early 1950s were instrumental in shaping modern jazz piano technique.

Following a partial recovery in the mid to late 1950s, Powell's relocation to Paris in 1959 contributed to the community of African-American expatriates fleeing racism and barriers to a higher standard of living.

Despite the friendship and protection of French jazz aficionado Francis Paudras, mental health crises and a troubled return to New York hastened his early death, aged 41, in 1966.

[9] Attempts to tell hospital staff he was a pianist who had "made records" led to his dismissal as a fantasist,[37] and in psychiatric interviews, he expressed feelings of persecution founded in racism.

[9] Powell may have been religious at this time; in a 1947 letter to fellow pianist and Catholic Mary Lou Williams, he lamented the challenges of his early life but felt that "God had used a spy" that "lifted me out of the depth of shame.

"[47]The first Blue Note session in August 1949 included trumpeter Fats Navarro, saxophone player Sonny Rollins, bassist Tommy Potter and drummer Roy Haynes, and it introduced Powell's compositions "Bouncing with Bud" and "Dance of the Infidels".

[34] Tracks from the two sessions included his compositions "Tempus Fugit" and "Celia", an up-tempo version of the jazz standard "Cherokee", "Get Happy", and "All God’s Chillun Got Rhythm".

[52] After a bout of alcoholism and narcotic use in August 1951, he was arrested on what The Complete Bud Powell on Verve author Peter Pullman describes as false marijuana charges.

[56] In February 1953, Powell entered the guardianship and financial management of Oscar Goodstein, owner of the Birdland nightclub,[53] but saw his health and piano playing affected by the antipsychotic medication Largactil, which he was prescribed as treatment for schizophrenia.

[63] Powell and Charlie Parker developed a rivalry that resulted in feuding and bitterness on the bandstand, likely caused at least in part by the pianist's worsening physical and mental health.

[66] By mid-1954,[34] Powell had resumed sessions for Norgran and Verve, recording alongside Duvivier, Taylor, Roach, Percy Heath, Lloyd Trotman, Art Blakey, Kenny Clarke, and Osie Johnson, in a series of albums produced for the two labels.

[55] Jazz historian Pierre-Emmanuel Seguin suggested that the removal of guardianship was an intentional move by Goodstein to marry Powell to Edwards and continue to control his musical engagements by proxy.

Nat Hentoff, writing for DownBeat, noted that during the Tour, Powell's style appeared to have become calmer and more lucid, contrasting with the turbulence of his playing in previous years.

[75] In the 1956 DownBeat critics' poll of jazz pianists, Powell took a narrow second, slightly edged out by Art Tatum; but he placed higher than Erroll Garner, Earl Hines, John Lewis, and Count Basie.

[78] In November, he began a tour of Europe with the Birdland All-Stars in addition to Miles Davis, the Modern Jazz Quartet, and Lester Young starring throughout the performances.

[79] His performances in Paris, and particularly at the Salle Pleyel, were short due to his ill health, but they influenced pianists René Urtreger and Francis Paudras and contributed to the growing jazz scene in France.

[80] Hentoff remarked that, in his opinion, Powell's constant touring was bad for his mental health, and that he needed psychotherapy while traveling due to the "grueling" nature of nightly performances.

[92] In December, Powell joined Art Blakey's Jazz Messengers for a recorded concert released as Paris Jam Session (1961) and contributed two of his compositions, "Dance of the Infidels" and "Bouncing with Bud", to the performance.

[115] A benefit concert was held to raise funds for his hospital stay; Johnny Griffin, Donald Byrd, Sonny Criss, and Jean-Luc Ponty performed.

[116] Powell completed further recording dates, including two with Paudras on makeshift brushes, during his last year in France; a further live engagement with Griffin in Jullouville was released on Mythic Sound as Holidays in Edenville.

[9] His engagement at Birdland with drummer Horace Arnold and bassist John Ore began on August 25[9] and included a repertoire of both jazz and classical music, particularly Bach.

[9][122] Powell's guardianship was transferred from Paudras to Bernard Stollman of ESP Records upon returning to New York,[106] and with the exception of hospital visits, he remained at Barnes's home until shortly before his death in 1966.

[25][125] However, his Town Hall performance received positive feedback from attendee Dan Morgenstern, who noted, "his final selection, 'I Remember Clifford', was extremely moving ... Powell hasn't lost his marvelous touch and sound, and everything he played revealed a sense of balance and proportion.

[8] His funeral was celebrated on August 8, 1966, with several bands playing through the streets of Harlem and arriving at Powell's former church; performers included trombonist Benny Green, trumpeter Lee Morgan, saxophonist Jim Gilmore, pianist Barry Harris, bassist Don Moore, and drummer Billy Higgins.

Patrick Burnette notes that Powell and Elmo Hope were "credited with creating the modern piano style of single-note right hand runs and left-handed chordal punctuation.

"[4] According to drummer Kenny Clarke, many of Monk's compositions were written in collaboration with Powell, and even pianists who did not adopt the bebop style, such as Duke Ellington, visited his home in Willow Grove regularly to hear him play.

[141] Tom Piazza noted for The New York Times that Powell played with "a Romantic's imagination [but] a classicist's precision and [with] an awesome, sometimes frightening, intensity" and was a "lifelong Bach devotee".

[144] The book was the basis for Round Midnight, a film inspired by the lives of Powell and Lester Young, in which Dexter Gordon played the lead role of an expatriate jazzman in Paris.

"[12] Powell was also praised by Art Blakey, Don Cherry, Kenny Clarke, Erroll Garner, Hampton Hawes, Freddie Hubbard, Carmen McRae, Max Roach, Sonny Rollins, Randy Weston, and Tony Williams.