The city of Rialto was incorporated on November 17, 1911. In 1939, the police department employed only two sworn officers. In 1945, the police department employed four sworn officers and serviced five square miles with a population of 3,000.
A new police facility was dedicated on November 20, 1973. The police facility housed less than half of the department's current personnel. In 1976, the police department's service area had grown, to 16 square miles, with a population of 32,000 people.
Today, the department employs 176 total employees. The department services 28.5 square miles with a population of over 100,000 people.