Paul Smith, a jazz pianist who accompanied many top singers and who provided the sensitive touch and rhythmic spark behind many of Ella Fitzgerald’s most acclaimed performances, died June 29 at a hospital in Torrance, Calif. He was 91.

He had cancer and died of heart ailments, his publicist, Alan Eichler, said.

Smith, whose career lasted more than 70 years, worked with two of the biggest musical acts of the 1940s, the Andrews Sisters and the Tommy Dorsey Orchestra, before settling in Hollywood, where he performed on the soundtracks of hundreds of films and television shows.

He stood an imposing 6-foot-5 and could span 12 notes on the piano with each hand. Despite his physique, Smith was known for a delicate touch at the keyboard that few could match. He made more than 50 recordings as a leader of his own groups, but he spent much of his career working in the shadow of such top-flight singers as Sarah Vaughan, Nat “King” Cole, Doris Day, Bing Crosby, Jo Stafford, Rosemary Clooney, Anita O’Day and Sammy Davis Jr.

Smith’s most significant association was with Fitzgerald, the jazz singer he accompanied off and on from 1956 to 1990. Fitzgerald’s biographer, Stuart Nicholson, called Smith “a massively accomplished pianist who at the time was perhaps the studio musician most in demand on the West Coast.”

He was the pianist on many of Fitzgerald’s most celebrated performances, including 1960’s “Live in Berlin,” which contains a high-spirited version of “Mack the Knife” in which Fitzgerald forgets the lyrics and improvises through the song for more than four minutes.

“And now Ella … and her fellas, we’re making a wreck, what a wreck of ‘Mack the Knife,’ “she sings at one point.

“You won’t recognize it,” she laughingly sings near the end of the tune, “it’s a surprise hit.”

In fact, the butchered version of “Mack the Knife” spent 14 weeks on the pop charts and garnered Fitzgerald two Grammy Awards for best vocal performance.

Smith was also at the keyboard for many of Fitzgerald’s classic “Song Book” albums of the 1950s and 1960s, in which she interpreted the works of various composers, including Cole Porter, Duke Ellington, Irving Berlin and the songwriting team of Richard Rodgers and Lorenz Hart, as well as that of George and Ira Gershwin.

In 1960, Smith and Fitzgerald recorded an album that became known as “The Intimate Ella.” It was little known until after its re-release in the 1990s, when it became recognized as one of the singer’s most emotionally expressive recordings.

Smith’s survivors include two children from his first marriage, a son from his second marriage, eight grandchildren; and two great-grandchildren.