Larkspur is a city in Marin County, California. Larkspur is located 3 miles (4.8 km) south of San Rafael, at an elevation of 43 feet (13 m). As of the 2020 Census, the city's population was 13,064. The city has a total area of 3.24 sq mi (8.4 km2), of which 3.03 sq mi (7.8 km2) is land and 0.22 sq mi (0.6 km2) (6.66%) is water.