The Pleasant Hills Public Library was opened in November 1945 in a small room on the second floor of the Fire Station on Route 51. Mrs. Leland B. Hubbs was instrumental in its founding, and most of the books were donated. Funds were raised by book sales, teas, and bridge groups, and in 1950, the "Friends of the Library" was organized to raise money for the library. More space became available at the Fire Station, and service was provided to residents 15 hours a week from a collection of 5,000 books.

In 1963, the Bell Telephone Building on Old Clairton Road was purchased by the borough as a new home for the library. Initially, one floor was used, but within a few years, the lower floor was opened as a Boys and Girls Room. Now the library was open 35 hours a week and housed a book collection of more than 40,000 volumes.

In 1995, weekly operating hours were increased to 48. Due to space constraints, the book collection was maintained at approximately 43,000 volumes.

At the end of October 1997, the library closed for 4 months to undergo an extensive renovation project. The library reopened in March 1998 with a new program room, a local history room, a comfortable reading area, office space, and additional room for the collection. Including audio-visual material, the library collection now stands at approximately 55,000 items.