The response from across the world of entertainment was pretty unanimous, with many taking to Twitter and Facebook to express their backing for the president's stance.
Below, we round up some of the reaction to the news from stars from the world of music, movies, TV and beyond.
"Obama, congratulations on being the first sitting President to support marriage equality. Feels like the future, and not the past. #NoFear"
Jane Lynch (actor)
"Pretty darn happy today. Thanks Mr President, for supporting the dignity of my family and so many others!"
Molly Ringwald (actor)
"Obama, well done you. :)"
Nancy Sinatra (musician)
"If you believe in equal rights for ALL Americans you had better vote for President Obama. The other side won't help you... President Obama endorses #MarriageEquality! Let's stand behind him."
Le Tigre (musicians)
"Congratulations, Barack Obama... Maybe he thinks he'll get invited to Beth's wedding."
Stuart Milk (nephew of Harvey Milk and co-founder of the Harvey Milk Foundation)
"We once again applaud the President as the fierce champion of human rights that he promised to be - promises kept - that is the story, courage that has been his been his example. Once again the message from the US Presidency is- we celebrate our diversity, we embrace full equality."
Kevin Smith (filmmaker)
Dear Mr.President, I quote the copy store clerk in JERRY MAGUIRE: "That's how you become great, man. Hang your balls out there." #UgotMyVote
Jason Alexander (actor)
"Mr. President - I applaud you. A righteous and courageous stance."
Neil Patrick Harris (actor)
"President Obama announces his support for same-sex marriage. ... Bravo, Mr. President, and thank you."
Eliza Dushku (actor)
"President @BarackObama #THANKYOU for your support of equal rights marriage! RT & show the#POTUS some love, guys-n-gals!!#FreedomToMarry"
Ellen Page (actor)
"Yes! Go Obama!#MarriageEquality #LGBT"
Holly Johnson (musician)
"I'm with Obama endorsing #Gaymarriage ... If you want it ;)"
Judy Blume (author)
"Also glad to hear Obama now says Yes to same sex marriage!"
Janelle Monae (musician)
"Thank you President Obama! Equal/Civil Rights for us all."
Danny DeVito (actor)
"No words can express my joy with Obama and Biden standing for the rights of every individual to marry and be treated with equality. Go team."
Wanda Sykes (writer, TV star)
"Thank you President Obama for supporting marriage equality. Can't explain how much this means to me, my wife, and our kids.#Obama2012"
Gareth Thomas (rugby player)
"Great words from Obama. Realising that in these days it's good to support love,when there is so much hate. #equality "
Cyndi Lauper (musician)
"President Obama continues to be a true leader for equality and I have never been prouder to call him my president than I am today."
Vincent Frank (musician)
"Obama thank you for making an incredibly positive mark on history."