Martinez is a city located in the East Bay region of the San Francisco Bay Area in California, United States. It serves as the county seat of Contra Costa County and is situated on the southern shore of the Carquinez Strait. As of the 2020 census, the city had a population of 37,287.
The city was founded on Rancho El Pinole and takes its name from the Californio ranchero Ygnacio Martínez. It is primarily recognized for its historic center and its waterfront area.