The Detroit Police Department (DPD) is the primary law enforcement agency of the city of Detroit, Michigan, United States. Founded in 1865, it has nearly 2,630 officers, making it the largest law enforcement organization in the state. In addition to 2,630 sworn-officers, the Department has filled 760 of 823 non-sworn positions such as dispatchers and Real Time Crime Center analysts.

Town constables were appointed in the territory for Detroit starting in 1801. During the American Civil War, the city's racial tensions escalated, and protests against the draft led to the Detroit race riot of 1863. The riots resulted in two deaths, the destruction of 35 buildings, and over 200 Black residents left homeless. Although a formal Police Commission had been established in 1861, the city responded to the violence by officially creating a full-time police force, with the first forty policemen beginning work in 1865. However, the department remained predominantly white well into the late 20th century.

In 1893, the department hired its first policewoman (Marie Owen) and its first black policeman (L. T. Toliver). The Detroit Police Department established a Women's Division in 1921 that was tasked with cases of "child abuse, sexual assaults, juvenile delinquency, and checking establishments for illegal minors." Female officers were not allowed to work on criminal cases unless accompanied by male officers until 1973, after a series of discrimination lawsuits prompted changes in department policy.

In 1928, the Detroit Police Department became the first police department in the country to utilize radio dispatch in their patrol cars. The system used a one-way radio in a single police car to broadcast messages from headquarters. A historical marker at Belle Isle Park describes the new advancement in technology.

In February 1940, Mayor Richard Reading, the Superintendent of Police, the county sheriff and over a hundred more were indicted on corruption charges. The Mayor was accused of selling promotions in the department. Eighty officers were accused of protecting illegal gambling operations in the city. In the end, the Mayor served three years in jail, ending in 1947.

In 1957, the Detroit Police Department employed 5,000 policemen and operated a fleet of ambulances to respond to medical emergencies.

In 2000, the Detroit Free Press published a series of articles after a four-month investigation into fatal shootings by Detroit police officers. At the time, Detroit had the highest rate of police-involved shootings of any large city in the United States, surpassing New York, Los Angeles, and Houston. The city requested an investigation by the United States Department of Justice into the department's handling of deadly force incidents. By 2001, the Justice Department's investigation had uncovered issues with the department's arrest and detention practices as well. Between 2003 and 2014, the Detroit Police Department was placed under federal court oversight by the Justice Department as the result of allegations about excessive force, illegal arrests and improper detention. This process cost the city of Detroit more than $50 million. By 2014, the department's use of force had been "seriously reduced" and the U.S. District Judge overseeing the case stated that the Detroit Police Department had "met its obligations" for reforms.

In 2005, the department's thirteen precincts were consolidated into six larger districts as a cost-cutting measure. The department restored a number of precincts in 2009 after citizens complained about the change. In 2011, it was announced that the Detroit Police Department would be reverting to the original precinct structure, with officials citing "gap[s] in services" and concerns over the new command structure.