Scavullo was preparing for an assignment when he complained of feeling weak, and then collapsed, Sean Byrnes said.
Known for works ranging from enamel-on-canvas photo silkscreens to portraits of celebrities such as Grace Kelly and Elizabeth Taylor, Scavullo was also recognized for his photographs of children. One of the most famous was his 1975 portrait of a young Brooke Shields.
Byrnes said his partner's work was guided by his love of beauty and children - themes Scavullo himself cited in a 1985 interview with The Associated Press.
"I have a passion for taking pictures of beautiful women," he said in the interview. "I was fascinated when my mother got done up. My mother made the transformation from Cinderella every day of her life."
Born Jan. 16, 1921, on Staten Island, Scavullo was one of five children whose father owned the old Central Park Casino. As a youth he got a job assisting the fashion photographer, Horst, and learned much of his craft from him.
He later worked for Vogue and Seventeen magazines before launching a lucrative and lengthy career that included photographing covers for Cosmopolitan, Harper's Bazaar and other magazines. At the peak of his career he commanded as much as $10,000 a sitting.
But Scavullo was most known for the photos he did for Cosmopolitan. He said the pictures eclipsed the rest of his work.
"It became an icon, and I became very famous because of the cover," Scavullo said in a biography on his Web site. "Everybody knew the Cosmo girl, and everybody wanted to be the Cosmo girl."
Album cover photographs Scavullo took include those for Diana Ross' "Diana," showing her with wet hair, a wet T-shirt and no makeup, and Edgar Winter's "They Only Come Out at Night," the first rock 'n' roll cover with full drag makeup, according to his Web site.
Etheleen Staley, director of the Staley-Wise Gallery in Manhattan, which handled Scavullo's work, remembered the photographer as a hard worker connected with the New York social elite.
"He really did high-quality work, and he got to be famous as a personality because he was tied in with the Studio 54 crowd, like Halston and Liza Minelli," she said.
Scavullo had been preparing for an exhibit in Miami at the end of the month and was working on a limited-edition series of portfolios.