Republican incumbents Jeff Denham, David Valadao, Steve Knight, Mimi Walters, and Dana Rohrabacher (who had been elected to fifteen terms) were all defeated.

50.45% (eligible voters) Results of the 2018 United States House of Representatives elections in California by district:[7] Doug LaMalfa Republican Doug LaMalfa Republican The 1st district is based in inland Northern California and includes Chico and Redding.

After advancing to the general election, Democratic candidate Audrey Denney was forced to pause her campaign for emergency tumor-removal surgery in August,[12] but returned in time to debate LaMalfa in September.

However, CDP staff refused to accept the forms after it was alleged they closed doors early to prevent the submission.

California allows candidates to include their professional description under their names on the ballot, however Regina Bateson later challenged Morse's ballot designation title of "National Security Fellow" at the Sacramento Superior Court after months of controversy that Morse, who had not worked in three years, was "fluffing" her credentials.

Organizations Local officials Individuals State officials Labor unions Organizations Mike Thompson Democratic Mike Thompson Democratic The 5th district is based in the North Bay and includes Napa, Santa Rosa, and Vallejo.

California's 7th district was included on the list of Democratic-held seats being targeted by the National Republican Congressional Committee in 2018.

California's 10th district was included on the list of Republican-held seats being targeted by the Democratic Congressional Campaign Committee in 2018.

As a minority, millennial female running against an established male politician, Heng received a number of comparisons to Alexandria Ocasio-Cortez.

[93] Heng gained notoriety during the campaign for aggressive attack ads, including one where she depicted a silver-haired man who resembled Costa walking on a sidewalk in red high heels, which prompted questions of sexism.

[94] More controversially her campaign ran an ad featuring images of the Cambodian genocide, part of her family heritage.

This ad was banned on Facebook and Twitter, leading to conservative claims of social media bias and unjustified censorship.

David Valadao Republican TJ Cox Democratic The 21st district is based in the Central Valley and includes Hanford and parts of Bakersfield.

California's 21st district was included on the list of Republican-held seats being targeted by the Democratic Congressional Campaign Committee in 2018.

[101] Democrat Emilio Huerta, who ran for the seat in 2016 and was planning to run again, dropped out shortly before Cox entered the race.

[102] Organizations U.S. executive branch officials U.S. senators U.S. representatives State officials Labor unions Organizations On election night, Valadao held an 8-point lead, the Associated Press and other news networks called the race for Valadao, and Cox conceded.

[108] California's 22nd district was included on the list of Republican-held seats being targeted by the Democratic Congressional Campaign Committee in 2018.

California's 24th district was included on the list of Democratic-held seats being targeted by the National Republican Congressional Committee in 2018.

California's 25th district was included on the list of Republican-held seats being targeted by the Democratic Congressional Campaign Committee in 2018.

Organizations Adam Schiff Democratic Adam Schiff Democratic The 28th district is based in the northern Los Angeles suburbs and includes Burbank, Glendale, La Cañada Flintridge as well as parts of central Los Angeles.

California's 36th district was included on the list of Democratic-held seats being targeted by the National Republican Congressional Committee in 2018.

Organizations Ed Royce Republican Gil Cisneros Democratic The 39th district straddles the Los Angeles–Orange–San Bernardino tri-county border and includes Chino Hills, Diamond Bar, and Fullerton.

U.S. representatives Individuals Local officials U.S. representatives State legislators Individuals Nanette Barragán Democratic Nanette Barragán Democratic The 44th district is based in south Los Angeles County and includes Carson, Compton, and San Pedro.

Mimi Walters Republican Katie Porter Democratic The 45th district is based in inland Orange County and includes the cities of East Anaheim, Irvine and Mission Viejo.

California's 45th district was included on the list of Republican-held seats being targeted by the Democratic Congressional Campaign Committee in 2018.

Organizations U.S. representatives State officials Alan Lowenthal Democratic Alan Lowenthal Democratic The 47th district encompasses Long Beach, Catalina Island, and parts of western Orange County, including Garden Grove and Westminster.

California's 48th district was included on the list of Republican-held seats being targeted by the Democratic Congressional Campaign Committee in 2018.

California's 49th district was included on the list of Republican-held seats being targeted by the Democratic Congressional Campaign Committee in 2018.

California's 50th district was included on the list of Republican-held seats being targeted by the Democratic Congressional Campaign Committee in 2018.

California's 52nd district was included on the list of Democratic-held seats being targeted by the National Republican Congressional Committee in 2018.