Jean 'John' Gagnon made his fortune in trucking business before becoming involved in hockey. Gagnon became the majority owner (50%) of the Roanoke Express in 1993. He was removed from his position as the President of the Roanoke Express on April 19, 1996 due to his involvement in becoming the majority owner of another CHL expansion franchise, the Mississippi Sea Wolves, in 1996.

Gagnon sold his majority stake in the Roanoke Express in March 1997. He became the majority owner of yet another ECHL franchise, the Dayton Bombers, after acquiring it from E.A. 'Bud' Gingher and Arnold Johnson in July 1998. The ECHL revoked the franchise from him in September 2002 due to unpaid bills.

He sold the Mississippi Sea Wolves to a group led by minority owner Lenwood S. Sawyer in June 2002. At the same time, he teamed up with Michel Cadrin to lease an existing ECHL franchise from David Elmore and Donna Tuttle. This franchise became known as the Lexington Men O'War.

He was named the General Manager and the Vice President of the franchise, only to resign from these positions in September, after the ECHL took over the Dayton Bombers. His involvement with the Lexington Men O'War came to an end in November 2002 when the suspended indefinitely by the ECHL.

Family relations
Son: Jean-Sébastien Gagnon