[2] Sagamihara is the third-most-populous city in the prefecture, after Yokohama and Kawasaki, and the fifth most populous suburb of the Greater Tokyo Area.

During the Edo period, the lands around Sagamihara were tenryō territory theoretically administered directly by the Tokugawa Shogunate in Edo; however, in reality, the area was a patchwork of small fiefs held by various hatamoto, as well as exclaves under the control of the Ogino-Yamanaka Domain and Karasuyama Domain.

The Kōza District portion was administratively divided into six villages on April 1, 1889 with the creation of the modern municipalities system.

A further merger on March 11, 2007, joined Fujino and Shiroyama with Sagamihara, thus geographically unifying the city, and dissolving former Tsukui District.

In 2010, Sagamihara was redesignated as a government ordinance city and split into three wards Midori-ku, Chūō-ku, and Minami-ku.

On July 25, 2016, 19 people were killed and 26 injured in a mass stabbing incident at a disabled care home in the city by Satoshi Uematsu, the perpetrator.

[6] Sagamihara has a mayor-council form of government with a directly elected mayor and a unicameral city council of 49 members.

[7] In terms of economy and geography such as railroads and roads, Sagamihara has stronger ties with Tokyo than other cities in the prefecture, especially with the Tama area such as Machida and Hachioji.