Mary Jo Kennedy, 58 was there with her wife Jo-Ann Shain, 60, and their daughter Aliya Shain, 25.
She came with a sign that could be flipped either way and was holding up the side that says "SCOTUS made our family legal".
They have been together 31 years and got married the day it became legal in New York.
Others were not celebrating.
"We mourn for America's future, but we are not without hope," said Tim Wildmon, president of American Family Association, in a statement.
Said. Tony Perkins, president of the Family Research Council: "Time is not on the side of those seeking to create same-sex 'marriage.' As the American people are given time to experience the actual consequences of redefining marriage, the public debate and opposition to the redefinition of natural marriage will undoubtedly intensify."
The federal marriage law had been struck down by several federal courts, and the justices chose to take up the case of 84-year-old Edith Windsor of New York, who sued to challenge a $363,000 federal estate tax bill after her partner of 44 years died in 2009.
Windsor, who goes by Edie, married Thea Spyer in 2007 after doctors told them Spyer would not live much longer. Spyer had suffered from multiple sclerosis for many years. She left everything she had to Windsor.
Windsor arrived at a news conference in New York after the ruling to applause from her supporters and said she felt "joyous, just joyous."
Windsor would have paid nothing in inheritance taxes if she had been married to a man. Now she is eligible for a refund.