The star has said she didn't want to wed until everyone in California could.
Among the rejoicing was a proposal. Kristen Bell tweeted: "@daxshepard will you marry me? Xo #marriageequality #loveislove."
Bell has been vocal about not marrying until everyone in the state of California can marry. "We'll wait until California gets on the right side of history," she said last August. So it looks like she's making good on her word.
(We'll have to see if this also paves the way for Brad Pitt, who told Ellen DeGeneres in 2011, "I've said, 'We would not be getting married until everyone in this country had the right to get married.' "
Other celeb reaction on Twitter:
Ben Affleck: "Big news from the Supreme Court. Goodbye #DOMA #Prop8. Hello #equality."
Lady Gaga: "We stand tall today.#DomaStruckDown So many fought for so long. Be proud, the prejudice are now the minority."
Leonardo DiCaprio: "Historic day. Well done ?#SCOTUS?. RT ?@GLAAD?: Supreme Court affirms that ?#DOMA? is unconstitutional!"
Joan Rivers: "Any straight person complaining about the Supreme Court striking down DOMA should be forced to hire a heterosexual wedding planner."
Neil Patrick Harris: "DOMA-it-just-lost-O Mr. Roboto!"
Ellen DeGeneres: "It's a supremely wonderful day for equality. Prop 8 is over, and so is DOMA. Congratulations everyone. And I mean everyone."
Andy Cohen: "I never dreamed I would see this day. The whole world has changed for us all. I can't believe it!! #DOMA #Equality"
Lena Dunham: "Don't wanna traffic in stereotypes but let's be real: I'm gonna love a gay wedding."
Piers Morgan: "RIP bigotry. #SCOTUS #DOMA"
Nia Vardalos: "I'll do the floral bouquets! RT @bouska: BREAKING! #Prop8 dismissed! Marriage equality returns to California!"
Perez Hilton: "YES!!!!!!!!!! California has marriage for all!!!!!!!!!!!!!!!!!"
Sarah Hyland: "Proud to be an American on a day like today. #DOMA found unconstitutional. Equality and love overrule"
Seth Meyers: "DOMA and Prop 8 should get married."
Tom Arnold: "Today is a proud day for America. #DOMA #Prop8 #USA ... I bet some of the "Of course I would love to marry you if it were legal" dudes are crapping their pants today. #DOMA"
Rachel Zoe: "What a major step forward for #marriageequality—beyond excited & proud of this country today! #loveislove @BarackObama
Alyssa Milano: "A big day for equality and human rights. I'm smiling so big right now."
Jesse Tyler Ferguson: "Victory for marriage in California as #Prop8 is struck down. Small but substantial steps toward #MarriageEquality for all!"
John Stamos: "What a momentous day. All Americans are equal, no matter who you love. ?#LoveIsLove?"
Adam Lambert: "Down w DOMA! Something to be very proud of this upcoming July 4th. We are making beautiful progress for Equality! ?#proud?"
Russell Brand: "If you're gay married in California your gay marriage is now legal. Good. #allmarriageisabitgay?"