The team originated as the Orillia Pepsis in 1966, but changed their name to the Terriers in 1969.
The Terriers won the OHA Senior A playoff title in 1970 and 1973 and also won the Allan Cup as Canadian Senior A champions in the latter year, defeating the visiting St. Boniface Mohawks of Manitoba 4-1 in a best-of-seven final playdown series. They had lost the 1970 national final to the Spokane Jets.
The 1972-73 edition of the club featured a number of veterans like Mike Draper, Gary Milroy and Grant Moore, all of whom had been in place since the first season, 1968-69. Also on the team were: Claire Alexander, who later played for the Toronto Maple Leafs; Jim Keon, brother of then-Leaf captain Dave Keon; Blake Ball, who played Gilmore Tuttle in the 1977 film "Slap Shot"; and goalie Louis Levasseur, who went on to all-star status in the World Hockey Association.
Orillia dropped down to Intermediate A in 1979 and left that league in 1982.