The Houston Police Department (HPD) is the primary municipal law enforcement agency serving the city of Houston, Texas, United States, and some surrounding areas. With approximately 5,300 officers and 1,200 civilian support personnel it is the fifth-largest municipal police department, serving the fourth-largest city in the United States. Its headquarters are at 1200 Travis in Downtown Houston.

HPD's jurisdiction often overlaps with several other law enforcement agencies, among them the Harris County Sheriff's Office and the Harris County Constable Precincts. HPD is the largest municipal police department in Texas.

Houston was founded by brothers Augustus and John Kirby Allen in 1836 and incorporated as a city in 1837. As the capital city of the Republic of Texas, it quickly grew, and so did the need for a cohesive law enforcement agency. The Houston Police Department was founded in 1841. The first HPD badge issued bore the number "1."

The early part of the 20th century was a time of enormous growth for both Houston and for the Houston Police Department. Due to growing traffic concerns in downtown Houston, the HPD purchased its first automobile in 1910 and created its first traffic squad during that same year. Eleven years later, in 1921, the HPD installed the city's first traffic light. This traffic light was manually operated until 1927, when automatic traffic lights were installed.

As Houston became a larger metropolis throughout the 1930s and 1940s, the HPD found itself growing and acquiring more technology to keep up with the city's fast pace. The first homicide division was established in 1930. During that same year, the HPD purchased newer weapons to arm their officers: standard issue .44 caliber revolvers and two Thompson submachine guns. In 1939, the department proudly presented its first police academy class. The Houston Police Officers Association (HPOA) was created in 1945. This organization later became the Houston Police Officers Union. The first African American woman police officer on the force, Margie Duty, joined the HPD in 1953, starting in the Juvenile Division.

Some historians have asserted that the HPD enforced an oppressive racial system that targeted blacks for harassment and failed to protect the black community during the Jim Crow era. In Race and the Houston Police Department, author and academic Dwight Watson writes that "HPD zealously enforced racial segregation in Houston".

In 1967, a civil rights protest at Texas Southern University turned into what police say was a riot. One officer was killed and nearly 500 students were arrested. It was as a result of these riots that the still-active Community Relations Division was created within the HPD. In 1970, the Helicopter Patrol Division was created with three leased helicopters. That year also marked the department's first purchase of bulletproof vests for their officers. The HPD's first Special Weapons and Tactics squad (SWAT) was formed in 1975.

In 1982, the Houston Police Department appointed its first African-American chief of police, Lee P. Brown, who succeeded B.K.Johnson. Brown served as chief from 1982 to 1990 and later became the City of Houston's first African-American mayor in 1998. While Brown was considered a successful chief, he also earned the unflattering moniker "Out of Town Brown" for his many lengthy trips away from Houston during his tenure.