He had a 15-year career in the National Hockey League (NHL), playing for the Washington Capitals, Montreal Canadiens, New York Islanders and Florida Panthers.

In February 2008, Zedník sustained a life-threatening injury during an NHL game when the skate of his teammate Olli Jokinen accidentally sliced his common carotid artery.

Zedník made the Capitals' roster out of training camp in 1996 and scored his first career NHL goal in the season opener on October 5 against Ed Belfour of the Chicago Blackhawks.

Two hundred fans with dyed hair attended the game, at which Zedník scored his first career hat-trick against the Detroit Red Wings, who had not lost in Washington in ten years.

[4] After spending six seasons with the Capitals, Zedník was traded during the 2000–01 season, along with Jan Bulis and a first-round draft pick (used to select Alexander Perezhogin), to the Montreal Canadiens in exchange for Trevor Linden, Dainius Zubrus and a second-round draft pick (later traded to the Tampa Bay Lightning) on March 13, 2001.

Zedník's second stint back with the Capitals was short as he was dealt at the trade deadline to the New York Islanders for a second-round draft pick on February 26, 2007.

[6][7] His nomination coincided with an official announcement that Zedník signed to play for Lokomotiv Yaroslavl in the Kontinental Hockey League (KHL) for the 2009–10 season.

On February 10, 2008, in a game where the Florida Panthers were playing the Buffalo Sabres, Zedník suffered a severe and life-threatening injury.

Paramedics, who are on standby at every NHL game, stabilized Zedník while the home team doctor Les Bisson controlled the bleeding.