In 1788, when Allegheny County was formed, the area now known as Penn Hills was part of Pitt Township. On January 16, 1850, Robert Logan, Thomas Davison and Daniel Bieber were appointed by the court to review the boundaries of a new township to be formed from the northern part of Wilkins. This new township was formed and named Adams, until August 1850 when the action of the court was reconsidered to change the name to McNair Township. The name was again changed to Penn Township by Act of Assembly and approved on February 10, 1851. In 1958 Penn Township became Penn Hills Township, and in 1976 Penn Hills became a home rule municipality. The earliest population was given in 1860, when there were 1,821 people living in Penn Township. The population grew to 2,685 in 1870 and 3,291 in 1880.

Neighborhoods within Penn Hills include Blackridge, Churchill Valley, Crescent Hills, Eastmont, Eastvue, Laketon Heights, Lincoln Park, Milltown, Nadine, Newfield, North Bessemer, Penn Ridge, Point Breeze, Rosedale, Sandy Creek, Shannon Heights, Universal, Valemont Heights, Gascola, Shadow Shuttle, Frankstown West, Frankstown Estates, Eastwood, and Verona Hilltop.

Penn Hills has ten land borders, including Verona and Oakmont to the north, Plum Borough to the east and northeast, Monroeville to the southeast, Wilkins Township, Churchill and Wilkinsburg to the south and the Pittsburgh neighborhoods of East Hills to the south, Homewood North to the southwest and Lincoln–Lemington–Belmar to the west.

The Allegheny River borders Penn Hills to the northwest with two neighborhoods running adjacent across the way: O'Hara Township and the borough of Blawnox.

Penn Hills is served by the Penn Hills School District, which includes: Penn Hills Elementary School, Linton Middle School, and Penn Hills High School.