Michalek came to the Ottawa Senators via trade in the deal that sent Danny Heatley to the San Jose Sharks in 2010. He was one of four Ottawa Senators voted into the 59th NHL All-Star Game.

He represented the Czech Republic, winning a bronze medal, at the 2012 World Hockey Championship.

In the 2011-12 season he was first among Ottawa Senators with a career high 35 goals and ended the season third amongst Senators with 60 points for the year.