The fire, in the apartment he used as a work studio, was reported around 7 a.m., said Michael Parrella, a spokesman for the New York City Fire Department. Firefighters found his body, he said, adding that the cause of the blaze had not been determined.

Mr. Pollock's partner, Sheryl Fratell, said he had left their Manhattan apartment on Sunday to work in the studio, where he often stayed overnight.

Mr. Pollock's crowning achievement was an office chair characterized by a single aluminum band around its perimeter that held it together, structurally and visually. Massive numbers of the chairs have been sold since its introduction in 1963, and it remains a major piece of the prestigious Knoll Collection. Often simply called the Pollock chair, it has been displayed at the Metropolitan Museum of Art, the Smithsonian Institution and the Louvre, and has made millions in royalties for Mr. Pollock.

But for a designer who as a youth doggedly sought out giants of midcentury design — Eero Saarinen, Charles Eames, George Nelson and Florence Knoll — and got to work with all of them, the big idea wasn't money. "A chair, it's like a sculpture," he once wrote in a biographical sketch.

"It starts as a thought, and then becomes an idea, something I might think about for years," he later explained. "When the time is right, I express it on paper, usually as a simple line in space. Finally, it takes shape."

In an interview with the BBC after Mr. Pollock's death, Deyan Sudjic, director of the Design Museum in London, called him "the opposite of the celebrity designers of the 1980s — a kind of anti-Phillipe Starck." Mr. Pollock, he said, had produced designs for only a few chairs, but "what he did design was beautifully considered and detailed — designs that have that elusive quality of timelessness."

Mr. Pollock seemed to many to have vanished from the scene after designing several chairs in the 1960s and one in the 1980s that many consider classics. Some thought he was dead. But Jerry Helling, president of Bernhardt Design, a North Carolina furniture maker, kept thinking of Mr. Pollock's "really cool" chair, he said in an interview on Friday, and became obsessed with finding him. His second thought was: wouldn't it be wonderful if Mr. Pollock designed something for Bernhardt?

Mr. Helling found three dozen Charles Pollocks before tracking down the right one. As it turned out, Mr. Pollock "was frantically working all those years," Mr. Helling said. He just wasn't selling anything. Mr. Pollock jumped at the chance to create a chair for Bernhardt, Mr. Helling said.

What he came up with was the CP lounge chair, a sleek, contoured design. Mr. Pollock likened it to an old Jaguar. "The profile of the frame makes it look racy and fast, but you look inside and you see hand-sewn leather and burl," he said. "The chair has speed and craft."

The chair generated favorable comment at the International Contemporary Furniture Fair in New York in 2012, and was honored the next year by the Red Dot awards, an international competition.

Charles Randolph Pollock was born in Philadelphia on June 20, 1930, and moved with his family to Toledo, Ohio, as a child. As a boy, he made a motor in his basement using odds and ends. The family settled in Detroit, where Mr. Pollock attended Cass Technical High School and won poster contests. At 16, when his family moved again, to Muskegon, Mich., he chose to remain in Detroit, living in a boardinghouse, working on Chrysler's assembly line and going to school.

After graduation he received a scholarship to Pratt Institute in Brooklyn, where he used wire to fashion his furniture designs. George Nelson, considered a founder of American modernism in design, admired one of his sculptures when he came to lecture. Mr. Pollock went to his office and presented it to him as a gift, telling him he would like to work for him when he graduated.