California's 30th senatorial district is one of 40 California State Senate districts. The seat is currently represented by of .
The district encompasses the Gateway Cities region of southeastern Los Angeles County, including Downey, Norwalk, Bellflower, La Mirada, Santa Fe Springs, Los Nietos, Montebello, Pico Rivera, Whittier, Hacienda Heights, La Puente, Valinda, Avocado Heights, Industry, Rowland Heights, Walnut, and Diamond Bar, along with Brea in northeastern Orange County.
Due to redistricting, the 30th district has been moved around different parts of the state. The current iteration resulted from the 2021 redistricting by the California Citizens Redistricting Commission.