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 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.

Due to redistricting, the 9th district has been moved around different parts of the state.

The current iteration resulted from the 2011 redistricting by the California Citizens Redistricting Commission.