The couple announced in May their plans to wed after California's Supreme Court legalized gay marriage under the state's constitution.
"All I can remember is what the priest said; that this moment will never happen again. It's something to savor," Takei, 71, told People magazine Sunday night after the Buddhist ceremony, which was attended by about 200 of the couple's friends and family members.
The reception was on the grounds of the Japanese American National Museum, People.com said.
"I was fighting back the tears," Nichelle Nichols, who played Uhura on "Star Trek," told People. "But they came oozing out anyway. I'm so happy that they're both able to legally proclaim their commitment to one another after spending the past 21 years together."
Nichols served as maid of honor at the wedding and Walter Koenig, who played Chekhov on the popular science-fiction show, was best man.
Takei is famous for playing Sulu on the series.