After starting the COVID-19 shortened 2020–21 season with a 0.99 GAA, Mrázek left his fourth start 2 minutes and 47 seconds into the game after sustaining an upper-body injury when teammate Max McCormick bumped into him, knocking the net off. This was later confirmed to be a thumb injury, severe enough that it required Mrázek to undergo surgery. On April 4, 2021, Mrázek returned from injury for the Hurricanes, posting his third shutout of the season.
