He played in the National Hockey League (NHL) for the New York Rangers, Atlanta Thrashers and the Los Angeles Kings.

In 2000, Hnilička won the Calder Cup while playing for the Hartford Wolf Pack of the American Hockey League (AHL).

At the 1991 NHL entry draft he was selected 70th overall by the New York Islanders, and moved to North America in 1992, spending one season in major junior with the Swift Current Broncos of the Western Hockey League (WHL), helping them reach the 1993 Memorial Cup.

Signing as a free agent with the Atlanta Thrashers, he spent three easons with them, before being traded to the Los Angeles Kings in 2003.

He holds the Atlanta Thrashers/Winnipeg Jets franchise record for saves in one game with 53 that he achieved on 18 December 2001, against the Boston Bruins.