Frolík has previously played in the National Hockey League (NHL) with the Florida Panthers, the organization that selected him tenth overall in 2006, as well as the Chicago Blackhawks, with whom he won the Stanley Cup in 2013.

[citation needed] Frolík played two seasons in the Czech Extraliga for Rabat Kladno before being selected tenth overall in the 2006 NHL Entry Draft by the Florida Panthers.

[citation needed] On 9 February 2011, during Frolík's third season with the Panthers, he was traded to the Chicago Blackhawks (along with goaltender Alexander Salák) in exchange for Jack Skille, Hugh Jessiman and David Pacan.

[8] In the subsequent off-season, on 30 June 2013, Frolík was traded to the Winnipeg Jets in exchange for a third- and fifth-round pick at the 2013 NHL Entry Draft.

[9] He finished with 19 goals and 23 assists on in the regular season, but was held pointless during the Jets' four-game sweep at the hands of the Anaheim Ducks in the 2015 playoffs.

[12] As a free agent over the summer and approaching the 2021–22 season, Frolík accepted an invitation to attend the St. Louis Blues training camp on a professional tryout (PTO) contract on 18 September 2021.