The top seeds beat Croatia’s Ivan Dodig and Marcelo Melo of Brazil 3-6, 6-3, 6-4, 6-4.
The brothers, taking part in their 25th Grand Slam final and who also won Wimbledon in 2006 and 2011, had also claimed gold at the Olympics in 2012.
They now have 15 men’s doubles titles at the Grand Slams and extended their winning streak to 24 matches.
“We’ve been working hard and taking care of our bodies. We’ve put the game in the right perspective in our life. When we lose, it’s not the end of the world,” said Bob Bryan.
“He’s married; I have a family; I have a kid. We’re just playing for fun. We’ve done it all in the sport, and now we’re just out there taking swings and not living and dying with every win and loss.”
Mike Bryan said the brothers still have plenty of ambitions, including defending their Olympic title in 2016 in Brazil.
“Probably like to hit 100 titles. I think today was 91,” said Mike when asked to set out their future plans.
“Then maybe try to finish No. 1 ten times. This year would be nine, if we did it. We got a pretty good lead. Then try to get to Rio and get another medal.”
Ken McGregor and Frank Sedgman are the only pair to have completed the calendar Grand Slam back in the pre-Open era of 1951.