The first circulating library in Wauwatosa dates back to the 1850s, with the first collection housed at what is now known as the Little Red Store. It was a subscription-only service which later moved to a schoolhouse near Root Common Park.

The current library can be traced back to 1886 when Oliver Harwood bequeathed $2,525 in his will for the purpose of “Christian Education." A group of citizens used the money to form the Harwood Library and Lecture Association which additionally was financed through subscriptions. From 1886 to 1896, the Library was located in different buildings in the Wauwatosa village area. In 1895, J.S. and Charles Stickney, who owned a pickle company, along with H.B. Hunter, donated a $3,000 lot at the corner of Harwood Avenue and Milwaukee Avenue. The association erected a $4,000 building on the site in 1896. Member subscriptions of $2 annually continued to finance library operations and the Stickneys loaned one pickle factory employee to serve as a janitor. 

In 1897, Wauwatosa took over the operation of the Harwood Library and Lecture Association, renamed it the Harwood Library and it became a true public library.

Philanthropist Andrew Carnegie donated $6,000 to Wauwatosa in 1905. With the Carnegie donation the library nearly doubled in size and was renamed the Wauwatosa Public Library (WPL).

To accommodate increased usage and the size of its collection, the library building on Harwood Avenue was expanded and remodeled in 1927. In the early 1930s, two branch libraries were added to meet demand. One branch was located at 64th and North Avenue and the other was at 68th and Wells Street. The branch at 64th and North Avenue moved to 69th and North Avenue in 1950.

In 1957 a new Civic Center was completed, housing the current Library and City Hall on the corner of Wauwatosa and North Avenues. The site was on the previous estate of Frederick D. Underwood, former president of the Erie Railroad and prominent Wauwatosa native. The original library building on Harwood Avenue was razed the following year. The North Avenue branch closed when the new main library opened. The 68th and Wells Street branch moved a block north to North 68th Street in 1958.

In 1968, an addition doubled the size of the library. The branch at 68th and Wells closed at that time. Another expansion and remodeling in 1992 consolidated the library collections on the second floor and created the check-out desk on the first floor. A large public meeting room and shared entrance with City Hall rounded out the changes made in 1992.

In 1995, WPL became the first public library in Milwaukee County to offer access to the Internet. Digital books became available to the public in 2006.

WPL has a storybook-themed Story Time Room and a collaborative Student Commons area. The Wauwatosa Public Library Foundation was instrumental in raising funds for both projects.

In 2023, WPL became the first public library in Milwaukee County to eliminate overdue fines throughout its collection.

The Wauwatosa Public Library remains a vibrant and dynamic community resource serving a diverse population on the western edge of Milwaukee County.