Jeff Wickham, a son-in-law, confirmed Opel's death but declined to give a cause, The New York Times reported.
Opel, who joined International Business Machines Corp. as a salesman in 1949, was its chief executive from January 1981 to January 1985.
During his tenure leading IBM, the U.S. Justice Department dropped a 13-year antitrust lawsuit against the company, enabling it to compete more aggressively.
The company's revenue nearly doubled under his leadership, and competitors complained the company had become too powerful.
In 1983, Opel appeared on the cover of Time magazine with the headline "The Colossus That Works."
IBM, seeking to make an inexpensive PC that could get to market quickly, used an Intel microprocessor and a Microsoft operating system, and the PC quickly gained in popularity.
After Opel left IBM, small computers relying on microprocessors and standardized software became increasingly predominant, and prices of hardware fell.
IBM ultimately sold its PC business and some other hardware operations and now focuses on software and services.