As of the 2020 redistricting, California's 39th congressional district was geographically shifted to the Inland Empire in Southern California. It is within the western region of Riverside County.
Riverside County is split between this district and the 41st district. They are partitioned by the Corona Freeway, River Trails Park, Redley Substation Rd, Arlington Ave, Alhambra Ave, Golden Ave, Doheny Blvd, Bolivar St, Campbell Ave, Pierce St, Quantico Dr, Collett Ave, Buchanan St, Highway 91, 12397 Doherty Way-Magnolia Ave, BNSF Railroad, N McKinley St, N Temescal St, E 16th St, S Neece St, Indiana Ave, Skyridge Dr, Fillmore St, 2969 Fillmore St-La Sierra Ave, Cleveland Ave, McAllister Parkway, Corsica Ave, Hermosa Dr, John F. Kennedy Dr, Wood Rd, Colt St, Dauchy Ave, Van Buren Blvd, Bobbit Ave, Chicago Ave, Krameria Ave, 16510 Sendero del Charro-Mariposa Ave, Barton St, Cole Ave, Rider St, Greenwood Ave, Kabian Park, Goetz Park, Ethanac Rd, McLaughlin Rd, Sherman Rd, Tumble Rd, Watson Rd, Escondido Expressway, Mapes Rd, Ellis Ave, Antelope Rd, Rico Ave, San Jacinto River, Ramona Expressway, Lake Perris State Recreation Area, Gilman Springs Rd, Moreno Valley Freeway, Quincy St, Cloud Haven Dr, Holly Ct, Reche Vista Dr, Reche Canyon Rd, and Keissel Rd. The 39th district takes in the cities of Moreno Valley, Jurupa Valley, Perris, and Riverside, as well as the census-designated places Mead Valley, Home Gardens, Highgrove, March Air Reserve Base, Good Hope, and Meadowbrook
In January 2018, Republican incumbent Ed Royce announced his retirement. Royce's retirement created great uncertainty and interest in this election, due to the possibility of two candidates of the same political party winning California's jungle primary.
The primary election resulted in two candidates of different parties, with Republican Assemblywoman Young Kim and Democrat Gil Cisneros coming in first and second place respectively. After the general election, it took several days to gather and tally absentee ballots, but on November 17, Cisneros was the projected winner of the election.