[1] After graduating from Colgate in 1936, he was an English teacher and the head football coach at Kenmore High School in Buffalo, New York.

[2][3][4] From 1936 through 1946, his Kenmore teams compiling an outstanding record of 50–7 capturing Niagara Frontier League championships in 1943, 1944 and 1945.

In 1955, Offenhamer was recruited by University of Buffalo President Dr. Clifford C. Furnas to revive the school's football team.

Offenhamer was named by United Press International as Coach of the Week after the Bulls upset highly regarded Columbia University 34-14 on October 25, 1958.

produced several individuals who went on to distinguished professional careers, including Gerry Philbin, a member of the 1968 Super Bowl champion New York Jets, and Buddy Ryan who was on Offenhamer's staff as the defensive line coach.