Wyomissing is a borough in Berks County, Pennsylvania, United States, established on July 2, 1906. As of the 2010 census the population was 10,461, compared to 8,587 at the 2000 census. The population growth of the borough was largely due to its merger in January 2002 with neighboring Wyomissing Hills. Wyomissing is the most populous borough in Berks County.