Although Seattle's first library association was organized in August 1868, the library was not a regular branch of city government until 1891. In 1896, with the establishment of a new charter, the management of the library, previously under the control of a library commission, was transferred to the position of librarian, who reported to the mayor and city council. In 1899, after several moves, the library moved from the Rialto Building to the Yesler Mansion. After a 1901 fire destroyed the library and its entire collection, Andrew Carnegie donated $200,000 for a new central library building. He later contributed another $20,000 for furnishings. The new central library was dedicated in 1906 and stood between Fourth and Fifth Avenues and Madison and Spring Streets.

In 1909, the state legislature removed all libraries in the state from the jurisdiction of the municipal civil service commissions so that the library could select its own employees.

Several other Carnegie-financed branches opened in Seattle neighborhoods following the dedication of the central library. These included the Greenlake, University, West Seattle, Queen Anne, Columbia, and Fremont branches, all built between 1910 and 1921. The Yesler branch (now Douglass-Truth), which opened its doors in 1914, was the first city-financed branch library. By 1949, the library had 11 branches.

The 1949 earthquake damaged the main library, however, and it found temporary housing until 1960, when the new library (built on the same site as the old Carnegie library) was dedicated. The library was outgrowing its space by the 1990s, and, in 1998, taxpayers approved $196.4 million in bonds for a new Central library, as well as additions and modifications to Seattle's branch libraries. The Dutch architect Rem Koolhaas and his firm, Office for Metropolitan Architecture, were selected in 1999 to design the new 355,000-square-foot central library. The new Central branch of the Seattle Public Library opened in May 2004.