The origins of the Tacoma Police Department can be traced back to the appointment of Leonard Diller as City Marshal of what would become Old Tacoma in 1874. Following the incorporation of New Tacoma in 1880, Henry Williams became the first City Marshal of New Tacoma. In 1884, Old and New Tacoma combined to form the City of Tacoma. E.O. Fulmer, who had begun as City Marshal of New Tacoma in 1882, became the first City Marshal of the City of Tacoma. New Tacoma's combined police station and jail on the southeast corner of 12th Street and Cliff Avenue served as Police Headquarters until 1899.

City Ordinance No. 77 formally created the Tacoma Police Department on April 15, 1885. Under this ordinance, a chief of police was to be elected by the City Council. The person in this role would be responsible for identifying and hiring officers. Because the role of City Marshal was established by the City Charter, the City Attorney determined that the Chief of Police and City Marshal would continue to serve simultaneously without one taking precedence over the other. The Mayor, R.J. Weisbach, appointed himself Chief of Police while E.O. Fulmer remained City Marshal. In 1886, the City stopped paying Fulmer and he successfully took legal action for lost wages. An 1896 ordinance established funding for the police department at a rate of $25.00 per month.

The development of the police department followed patterns of change nationally. Horses and a bicycle squad preceded the acquisition of the department's first motor vehicles in 1910. During Prohibition, local police were said to have met bootleggers at the docks to safely escort them to their warehouses. As the Great Depression took hold, the Tacoma Police Department and Tacoma Fire Department challenged each other to a football game. Admission was charged and the money was used to purchase flour and beans to distribute to hungry families in Tacoma. In the 1940s, police were responsible for enforcing Executive Order 9066 by forcing local families of Japanese descent into incarceration facilities and confiscating their cameras, radios, and other banned items. Controversial "vice squads" were active in the 1950s. While some supported the work of cracking down on gambling and prostitution, the department was accused of using unlawful tactics and the entire squad was demoted to patrol by Mayor Ben Hanson. "Community based policing" was embraced by the department in the 1960s. Officers began wearing name badges and being assigned to specific neighborhoods. The department came under national scrutiny over tactics used by police during violent clashes with local Indigenous tribes over fishing rights in the 1970s. In the 1980s, there was widespread coverage in local media about racial discrimination and use of excessive force by Tacoma police officers. In the 1990s, officers staged a protest against Chief Phillip Arreola in response to his accusation that officers were covering up the misdeeds of other members of the force. The 2000s saw the establishment of the Marine Services Unit and the opening of a new headquarters at 3701 South Pine Street. In 2020, nationwide protests broke out in response to police violence against people of color. Locally, these protests intersected with the killing of Manuel Ellis, a Black man, by police in March 2020.

As of 2022, the Tacoma Police Department has the following mission statement: "To create a safe and secure environment in which to live, work, and visit by working together with the community, enforcing the law in a fair and impartial manner, preserving the peace and order in our neighborhoods, and safeguarding our Constitutional guarantees."