An undrafted player, Kořenář previously played for the San Jose Sharks and the Arizona Coyotes in the National Hockey League (NHL).

In July 2017, it was announced that Kořenář had signed an entry-level contract with the San Jose Sharks as an undrafted free agent after spending the 2016–17 season with the Lincoln Stars of the USHL.

[2] On 26 August 2020, Kořenář was assigned by the San Jose Sharks to HC Oceláři Třinec of the Czech Extraliga, on loan until the commencement of the delayed 2020–21 North American season.

[3] After being in net for the San Jose Barracuda and in the taxi squad for the 2020–21 season, he made his NHL debut on 10 April 2021, in a 2–4 loss to the Los Angeles Kings, playing the final period.

[8] As an impending restricted free agent with the Coyotes following the 2021–22 season, Kořenář opted to return to his homeland in agreeing to a two-year contract with HC Sparta Praha of the ELH, on 7 June 2022.