Schiff and Garvey ran in two separate elections: one for the full six-year term and the other for the remaining weeks of Feinstein's unexpired term. Schiff was well ahead in both races.
"Regardless of the way people may have voted, I want to make one thing clear: As your senator, I am committed to standing up for every Californian," Schiff said Tuesday night. "I am committed to taking on the big fights to protect our freedoms and to protect our democracy. California will continue to be at the forefront of progress, the bulwark of democracy, the champion of innovation and the protector of our rights and freedoms."
Democrats were favored to easily hold the seat in the liberal-leaning state where a Republican candidate hasn't won a Senate race since 1988, when President Ronald Reagan was in the White House. Schiff held an edge for months in campaign financing and polling over Garvey.
Still, the campaign represented a turning point in California politics, which was long dominated by Feinstein, former U.S. Sen. Barbara Boxer, former Gov. Jerry Brown and a handful of other veteran Democratic politicians. The result also means that California will not have a woman representing it in the Senate for the first time in more than three decades.
Speaking to supporters, Schiff promised to work in the Senate for safe neighborhoods and better schools and to reduce the menace of climate change. California is facing struggles, he said, but "together, there is no challenge we cannot overcome."
Garvey, in a concession speech, said his campaign succeeded in bringing attention to problems from rising crime to runaway spending on homelessness that has seen scant results. "We took a stand on what impacted California," Garvey said.
Schiff shaped his campaign around national issues including abortion rights while continuing to play a foil to Trump, calling the former president a threat to democracy. He also contrasted his years of experience in Congress - Schiff was first elected to the House in 2000 - against Garvey, a first-time candidate who positioned himself as an outsider with fresh perspective to deal with California's long-running homeless crisis, inflation and housing costs.
Garvey, a former MVP and perennial All-Star who played for the Los Angeles Dodgers and the San Diego Padres, called himself a "conservative moderate" who shouldn't be buttonholed into conventional political labels, an obvious pitch to independent and soft Democratic voters in a state where registered Republicans are outnumbered by Democrats nearly 2-to-1.
The Republican Party has struggled in the nation's most populous state for years, though it retains pockets of strength in rural areas, the Central Valley farm belt and parts of Southern California.
Democrats hold every statewide office and dominate the Legislature and congressional delegation by commanding margins. Republicans haven't won a statewide race in the state since 2006.
Garvey aimed a final advertising push at Latinos, who make up about a quarter of likely voters in California.
Feinstein, a centrist Democrat who was elected to the Senate in 1992, died at 90 in September 2023. Laphonza Butler, a Democratic insider and former labor leader, was appointed to the seat following Feinstein's death and decided not to seek a full term this year.
The Associated Press contributed to this report.