Belvedere is a residential incorporated city located on the San Francisco Bay in Marin County, California, United States. Consisting of two islands and a lagoon, it is connected to the Tiburon Peninsula by two causeways. At the 2020 census, the population was 2,126. The per-capita income of Belvedere residents in the year 2000 was $250,000, but currently the average income is $283,000, making it one of the highest-income cities in California and the eighth highest-income community in the United States. Belvedere and Tiburon share a post office and the 94920 ZIP code.

Marin County is located in the northwestern part of the San Francisco Bay Area of the U.S. state of California. As of the 2020 census, the population was 262,231. Its county seat and largest city is San Rafael. Marin County is across the Golden Gate Bridge from San Francisco, and is included in the San Francisco–Oakland–Berkeley, CA Metropolitan Statistical Area.