Mount Penn Borough is located in central Berks County at 40°19′46″N 75°53′26″W / 40.32944°N 75.89056°W / 40.32944; -75.89056 (40.329359, -75.890691),[4] bordered by the city of Reading to the west.

A non-contiguous piece of Lower Alsace Township also borders the south side of Mount Penn.

The borough is in a small saddle between the peak of Mount Penn to the north and 900-foot-high (270 m) Neversink Mountain to the south.

According to the United States Census Bureau, the borough has a total area of 0.42 square miles (1.1 km2), all land.

Attractions in the Preserve include the Pagoda, the William Penn Memorial Fire Tower, Antietam Lake Park, and numerous businesses and restaurants.

It follows Perkiomen Avenue through the center of the borough, leading west into downtown Reading and southeast to Pottstown.