Harmony is a borough in Butler County, Pennsylvania, United States. The population was 890 at the 2010 census. It is located approximately 30 miles (48 km) north of Pittsburgh.

Butler County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 193,763. Its county seat is Butler. Butler County was created on March 12, 1800, from part of Allegheny County and named in honor of General Richard Butler, a hero of the American Revolution. The county is part of the Greater Pittsburgh region of the state.