"The Seahawks family is saddened by the loss of Chuck Knox, and our deepest sympathies are extended to his wife, Shirley, and the entire Knox family", the team said in a statement Sunday.
He had been battling symptoms of dementia, the Seattle Times reported.
Knox was a three-time Associated Press NFL Coach of the Year (1973, 1980, 1984) and was also inducted into the Seahawks' Ring of Honor on September 25, 2005. The memories and accomplishments that Coach Knox left behind will continue to inspire us and Rams fans.
Besides the Seahawks, the coach nicknamed "Ground Chuck" took the Los Angeles Rams and the Buffalo Bills to the playoffs and was three times named National Football League coach of the year. Knox took the head coaching position in Seattle in 1983.
He guided four teams to conference championship games-the Rams three times in the 1970s and the Seahawks in 1983-but never reached a Super Bowl.
In 1984, the Seahawks went 12-4, but couldn't beat out John Elway's Broncos for the AFC West title. That was the site of his longest stint, nine years with the Seahawks that produced 80 wins, plus three more in four trips to the playoffs, and the first taste of sustained success for a franchise that had originated in 1976. But Marino and the Dolphins got their revenge in the divisional round, shredding the Seahawks 31-10. He was also inducted into the Seahawks' Ring of Honor in 2005.
Knox compiled a regular-season record of 186-147-1, and went 7-11 in the playoffs during his 22 seasons as a head coach.
Knox was born in the suburbs of Pittsburgh in 1932 and played college football at Juniata College in Huntingdon, Pennsylvania. He remained with the Jets until 1966, and was then offensive line coach with the Detroit Lions from 1967-1972.