In December 2021, the boundaries of the First District were redrawn by Los Angeles County’s Independent Citizens Redistricting Commission to reflect new and shifting populations.
| Cities | Unincorporated Areas | Los Angeles City |
| Alhambra | Avocado Heights | Angelino Heights |
| Azusa | Azusa | Atwater Village |
| Baldwin Park | Bassett | Boyle Heights |
| Covina | Charter Oak | Chinatown |
| Diamond Bar | Covina (portion) | Cypress Park |
| El Monte | East Los Angeles | Downtown |
| Industry | El Monte | Eagle Rock |
| Irwindale | Hacienda Heights | East Hollywood |
| La Puente | Industry Islands | Echo Park |
| La Verne (portion) | North Whittier | El Sereno |
| Los Angeles (portion) | Northeast San Gabriel (portion) | Elysian Park |
| Montebello | Pellissier Village | Elysian Valley |
| Monterey Park | Pomona | Glassell Park |
| Pomona | Rowland Heights | Highland Park |
| Rosemead | San Jose Hills | Historic Filipinotown |
| San Gabriel | South El Monte | Lincoln Heights |
| South El Monte | South San Gabriel | Little Armenia |
| Walnut | Valinda | Little Tokyo |
| West Covina | Walnut | Mt. Washington |
| West Puente Valley | Pico-Union (portion) | |
| Whittier Narrows | Silverlake | |
| Thai Town | ||
| University Hills | ||
| Westlake | ||