Wyomissing is a borough in Berks County, Pennsylvania, United States, adjacent to Reading. The borough was incorporated on July 2, 1906. As of the 2020 census, the population was 11,114, compared to 10,461 at the 2010 census. The growth was significantly larger between 2000 and 2010 largely because of its merger in January 2002 with neighboring Wyomissing Hills. Wyomissing is the most populous borough in Berks County.