Darlington is a borough in northwestern Beaver County, Pennsylvania, United States.

According to the United States Census Bureau, the borough has a total area of 0.1 square miles (0.26 km2), all land.

There were 130 housing units at an average density of 1,399.0 per square mile (540.2/km2).

32.0% of all households were made up of individuals, and 16.4% had someone living alone who was 65 years of age or older.

About 3.9% of families and 9.2% of the population were below the poverty line, including 10.9% of those under the age of eighteen and 9.7% of those sixty five or over.