California's 9th senatorial district is one of 40 California State Senate districts. It is currently represented by Democrat Tim Grayson of Concord.
The district encompasses most of Contra Costa County, including Concord, Antioch, Pittsburg, Bay Point, Martinez, Pleasant Hill, Walnut Creek, Lafayette, Danville, San Ramon, and Orinda; along with Castro Valley, San Lorenzo, and San Leandro in Alameda County.
It previously encompassed the East Bay and consists of the urban, coastal northwestern portion of Alameda County, and western portion of Contra Costa County, including Alameda, Oakland, Piedmont, Emeryville, Berkeley, El Cerrito, and Richmond; currently represented by the 7th district.
Due to redistricting, the 9th district has been moved around different parts of the state. The current iteration resulted from the 2021 redistricting by the California Citizens Redistricting Commission.