Sayama is located in south-central Saitama Prefecture. The Iruma River flows through the city.
During the Kamakura period, the area developed as a post station on the Kamakura Kaidō highway, as the dividing point on the routes to Kōzuke Province and Shimotsuke Province. The town of Irumagawa was established within Iruma District with the establishment of the municipalities system on April 1, 1889. On July 1, 1954, Irumagawa merged with the neighboring villages of Mizutomi, Kashiwahara, Okutomi, Hirokane, and Irima to create the city of Sayama.
The city was the location of the Sayama Incident, a 1963 murder and trial which resulted in the false accusation and conviction of an innocent man, a member of the Burakumin minority group, of murder.
Sayama is one of the major industrial centers of Saitama Prefecture, although it is also a bedroom community with over 15% of its population commuting to Tokyo for work. The city, along with neighboring Iruma, is a well known tea growing region, producing Sayama Tea.
Sayama is the location of an automobile assembly plant, which opened in 1964, for Honda/Acura vehicles, currently including the Fit, Honda Odyssey (international), CR-V, and RLX, and in the past the Accord, Prelude, Vigor, Inspire, Legend and Integra. The plant was briefly closed, but not damaged, following the March 2011 Tōhoku earthquake and tsunami, and restarted production in April 2011, albeit at lower production levels.