Finleyville is a borough in Washington County, Pennsylvania, United States, named for John Finley. The population was 375 at the 2020 census. It was built at the junction of Brownsville Road and the 'Washington Road' from Cox's Fort to Catfish Camp, now Washington, Pennsylvania. It was originally known as "Rowgalley" until after a large contingent of Scots-Irish came to town including a number of "Finleys." It is in the Peters Creek watershed.