The contest in the 39th Congressional District anchored in Orange County was a rematch from 2018, when Cisneros was one of seven Democrats who claimed GOP-held California districts that year.
Kim overcame President Donald Trump’s poor performance in heavily Democratic California, where he got only one-third of the votes.
Kim, a former state lawmaker, was born in South Korea and grew up in Guam. She joins Washington state’s Marilyn Strickland and California’s Michelle Steel as the first Korean American women elected to Congress.
Strickland, a Democrat, last week won the open 10th Congressional District southwest of Seattle. Steel, a Republican, claimed the 48th District in Orange County on Tuesday from Democratic Rep. Harley Rouda.