The 29-year-old touched in at 57.82 seconds to set a national record, Poland's PAP news agency reported.
Russia's Maria Kameneva finished second in the event on Thursday, with a time of 57.83, while Sarah Sjöström of Sweden claimed the bronze after clocking in at 58.05.
Tchórz's gold was her second medal of the competition in Kazan, after a bronze she earned two days earlier in the 4x50 m freestyle relay together with teammates Kornelia Fiedkiewicz, Dominika Sztandera and Katarzyna Wasick.
Team Poland has so far won five medals, one gold, one silver and three bronze, at the 2021 European Short Course Swimming Championships, which started in Kazan on Tuesday and run until Sunday.
Poland's Paweł Juraszek took the bronze in the men's 50m freestyle on Thursday.
On Wednesday, Poland's Wasick claimed the silver in the women’s 50m freestyle, and Jakub Majerski added a bronze to the tally after finishing third in the men's 100m butterfly.
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Source: PAP