He turned professional with the American Hockey League (AHL), initially with the Cincinnati Mighty Ducks before being assigned to the Grand Rapids Griffins.

Kopecký played four seasons with the Griffins before making his NHL debut with the Red Wings towards the end of 2005–06 on 28 February 2006 against the San Jose Sharks.

Kopecký lost his footing and hit the boards as he approached the Chicago blue line and Blackhawks defenseman Jim Vandermeer then fell on top of him.

Kopecký had previously worn the number 28 with Detroit, but switched to 82 after the Red Wings acquired free agent defenseman Brian Rafalski.

Replacing injured forward Andrew Ladd, Kopecký netted the 6–5 game-winning goal in the Game 1 victory of the 2010 Stanley Cup Finals against the Philadelphia Flyers.

The defending Stanley Cup champion Blackhawks desperately needed either a win in any fashion or an overtime/shootout loss to decisively clinch a playoff spot.

The Hawks lost the game 4–3 in regulation not gaining any points in the standings, but still clinched the eighth and final playoff spot due to a Dallas Stars 5–3 loss later that same day against the Minnesota Wild.

If the Stars had won their finale against the Wild, the defending Stanley Cup champion Blackhawks would've missed the playoffs entirely by one point and it would've marked the first time in Kopecký's career to have been on a non-playoff team.

[5] He did not return to the ice for the rest of the series and the defending Stanley Cup champion Blackhawks ultimately lost the first-round matchup in seven games.

However, on 27 June, the Blackhawks traded Kopecký to the Florida Panthers, who obtained the exclusive negotiating rights with the player until he was to become a free agent.

Despite the team struggles, Kopecký continued to stay productive individually having finished the abbreviated season by recording 15 goals and 12 assists for 27 points in 47 games played.