Darlington is a borough in northwestern Beaver County, Pennsylvania, United States. The population was 249 at the 2020 census. It is a part of the Pittsburgh metropolitan area.

Beaver County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 168,215. Its county seat is Beaver, and its largest city is Aliquippa. The county is part of the Greater Pittsburgh region of the state.