Sayama is located in south-central Saitama Prefecture, on the alluvial lowland of the Iruma River, which flows through the city towards the northeast (toward Kawagoe) .

Saitama Prefecture Sayama has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall.

On July 1, 1954, Irumagawa merged with the neighboring villages of Mizutomi, Kashiwahara, Okutomi, Hirokane, and Irima to create the city of Sayama.

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.

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, RLX, and Clarity and in the past the Accord, Prelude, Vigor, Inspire, Legend and Integra.

[8] Dai Nippon Printing Company, Ltd. imaging media division operates a large coating facility in the city.