Venus and Serena Williams made Olympic history as they became the first pair to win the women’s doubles three times.
Despite being short of their best form, they beat Andrea Hlavackova and Lucie Hradecka of Czech Republic 6-4 6-4.
Serena, 30, adds the doubles title to the singles gold she won on Saturday, and last month’s Wimbledon success.
She becomes only the third woman to win a pair of gold medals at the same Olympics – emulating Venus in 2000 and compatriot Helen Wills Moody in 1924.
The sisters first won the doubles at Sydney in 2000, did not defend their title four years later due to Serena being injured, and then won again in Beijing in 2008.
Venus, 32, believes they can go on to record a fourth victory at the Rio Games in 2016.
She said: “It’s incredible. Coming off Serena’s victory I think most of all we are happy to add to our country’s medal count and be a part of it.
“I would say this is more special than Wimbledon. I’m amazed she won the singles and our main goal was to win the doubles, so we got both and it’s amazing.
“We’re definitely planning on Rio. We’re going out with a bang in Rio. Hopefully we will make it four, you never know.”
The Czechs got off to a sluggish start when Hradecka’s first service game was broken.
The American duo, who withstood a break point as Venus served for the set, held on to take the opener.
BBC Sport’s Sam Smith: “They were wonderful scenes on Centre Court where the sisters have had so much success in the Wimbledon championships and now they have done the same in the Olympics. They have made history and who would bet against them doing it again in Rio in four years’ time?”
The fourth-seeded Czechs made a more resilient start to the second set but Hlavackova was broken for Venus and Serena to move 3-2 ahead and they never seemed in any danger of letting their advantage slip.
Serena said that the doubles title was always her priority at the Olympics.
“It was so exciting to win the singles, but like I said at the beginning of the tournament my goal was to get gold in doubles here,” she said.
“There’s something about standing next to Venus and holding that gold medal. Three times we have played, three times we have got the gold medal. So we are pretty stoked about it.”
In addition to winning five Wimbledon doubles titles together, the pair have each had five victories in the SW19 singles tournament.