Geoff Courtnall was signed by the Boston Bruins of the NHL as an undrafted free agent on July 6, 1983.

He played for the Bruins from the 1983–84 season to March 8, 1988, when he was traded, along with Bill Ranford, to the Edmonton Oilers for Andy Moog.

While in Edmonton, he helped the Oilers win the Stanley Cup in 1988, after facing his old team the Bruins in the finals.

After two seasons in Washington, Courtnall requested a trade, which was granted in the 1990 off-season when he was sent to the St. Louis Blues for Mike Lalor and Peter Zezel.

[2] In May 1990, while playing for the Capitals, Courtnall was accused of raping a 17-year-old girl outside a bar, alongside teammates Dino Ciccarelli, Scott Stevens, and Neil Sheehy.