On September 20, 1977, the Sabres traded Spencer to the Pittsburgh Penguins in exchange for Ron Schock. During his time with the Penguins, his offensive play declined drastically. His last seasons in the NHL came in 1978-79. He was sent down to the AHL to play for the Binghamton Dusters, Springfield Indians, and Hershey Bears and then he retired in 1980.