Venus and Serena beat French Open champions Paola Suarez and Virginia Ruano Pascual 6-2 7-5 in one hour and 20 minutes.
The title comes just one day after Serena beat older sister Venus in the final of the women's singles.
Serena beat Venus 7-6 (7/4) 6-3 on Saturday, ending Venus' dreams of a third successive championship.
It is the second Wimbledon doubles crown for the sisters, following their victory two years ago.
They have also won all four Grand Slam doubles titles - Australian, French Open, Wimbledon, US Open - and the 2000 Olympic gold.
But even mum Oracene is becoming harder to impress, as she was absent from Centre Court on Sunday for the first time since the tournament got underway.
"I get a little tired watching tennis all the time," admitted Oracene, who preferred to spend the day shopping in central London.