A native of Detroit and a graduate of Hillsdale College in Hillsdale, Michigan, his first job in radio was at WHLS in Port Huron, Michigan. Knorr purchased four Michigan radio stations, including WKMH, which broadcast Tigers games. In 1956, Knorr and John Fetzer led an ownership group intending to acquire the Tigers and Briggs Stadium from the Briggs family. The team was sold at a cost of US$5,500,000 with assurances of retaining Walter Briggs, Jr., who was given the position of executive vice president. In addition to being owner, Knorr also served as president in 1957 before being replaced by Harvey Hansen on April 19, 1957.
The team under Knorr's new direction supported integration of baseball, a position that was contrary to Walter Briggs's longtime segregationist stance. On June 6, 1958, Ozzie Virgil, Sr. became the first black player for the Tigers.
In late December 1960, Knorr, 47, died of burns suffered when he accidentally fell into a bathtub of scalding water while vacationing in a Fort Lauderdale, Florida, hotel. Upon his death, Fetzer became majority owner.
- "Fred Knorr Buys a Ball Club" Sports Illustrated, February 18, 1957
- "Radio Exec Dies of Burns" Florence Times-Union, December 27, 1960
- A picture of Knorr at WHLS in Port Huron hangs in the Knorr Family dining hall at Hillsdale College
- Time: All ($5,500,000) for Fun
- BaseballLibrary.com: Detroit Tigers
- The Detroit News: The day the Tigers finally integrated
- Associated Press, 28 December 1960