The cause was pneumonia, SeattlePI.com reported. Rosellini died Monday.
Rosellini, a native of Tacoma who worked his way through law school as a janitor, was elected to the state Legislature while still in his 20s. He was governor from 1957 to 1965.
During his first term as governor, Rosellini modernized Washington state prisons, mental hospitals and other institutions and helped create the University of Washington medical school, The Seattle Times said.
Throughout his career and into his retirement, Rosellini was dogged by charges he had misused his position to do favors for supporters and friends, the Times said. But in recent years, his birthdays became gatherings of former governors.
"Washington state lost one of its brightest stars today," Gov. Chris Gregoire said in a statement. "Governor Al Rosellini was a tireless leader who changed the state for the better in countless ways. My heart goes out to his family on this day of incredible loss."