His professional career lasted from 1985 until 2000, during which time he played for the Toronto Maple Leafs, Quebec Nordiques, New York Islanders, Tampa Bay Lightning, Detroit Red Wings and Chicago Blackhawks.

The Leafs had a memorable run to the Campbell Conference Finals, but after leading the best-of-seven series three games to two coming within one game of advancing to the Stanley Cup Finals, they lost to the Wayne Gretzky-led Los Angeles Kings, who were coached by Clark's cousin, Barry Melrose.

Clark managed a career-high 46 goals in 64 games for the Leafs during the 1993–94 season, playing on a line with Dave Andreychuk and Doug Gilmour.

In June 1994, with his value at an all-time high, Clark was traded to the Quebec Nordiques in a multi-player deal that notably involved a young Mats Sundin.

As a result, shortly before the beginning of the 1995–96 campaign, he was sent to the New York Islanders in a three-way trade that brought Claude Lemieux to Colorado and Steve Thomas to the New Jersey Devils.

In 1998 Clark signed as a free agent with the Tampa Bay Lightning, where he earned a spot on the North American All-Star team and went on to score 28 goals in 65 games.

Leaf fans gave their former captain a 90-second standing ovation after Clark barreled into the New Jersey Devils zone and hit the post in Game 1.

The Toronto Maple Leafs honoured the former captain by raising his legendary number 17 to the rafters on November 22, 2008, at the Air Canada Centre.