There was some late resistance - No.4 seeds Casey Dellacqua and Yaroslava Shvedova broke them while they tried to serve for the match at 6-3, 5-2 - but the No.1-seeded Hingis and Mirza broke right back to win the match, one last Hingis putaway at the net sealing the match and the title, 6-3, 6-3.
Hingis and Mirza now have five WTA doubles titles together since first joining forces at Indian Wells in the spring, including back-to-back Grand Slam doubles titles at Wimbledon and now the US Open.
It was Hingis' second time winning the US Open doubles title - her first came all the way back in '98.
"It feels like I'm doing it all over again," she said. "But I'm not thinking, 'Okay, the last time was 18 years ago.' What counts for me is right now, today, in this moment. I know I have the support and the trust that I have for her shots and for her game, and it builds up every time we step out together."
"We try to help each other out if the other one is struggling. That's kind of the key," Mirza said.
"We're happy to win our second Slam together. We didn't think that this was going to happen so soon. Hopefully we can keep building. We're the No.1 team in the world, so we have to keep building on this."
For Hingis, the victory gave her another milestone in her illustrious career. She now has a total of 20 Grand Slam titles across all three disciplines (five singles, 11 doubles and four mixed doubles).
"I was at the Hall Of Fame dinner last night and Pam Shriver was sitting next to me, and she's like, 'You know, I've got 22. I've got 22.' She was like going on about that one!" Hingis described.
"But it's amazing. I would have never thought I could go this far, especially this year, winning five Grand Slam titles - three in mixed doubles, now two in doubles. It just means so much to me, yeah."
She's just the third active player to hit 20 (Serena Williams has 36 and Venus Williams has 22).
Mirza now has a total of five Grand Slam titles - two in doubles and three in mixed doubles.
A double double once again. Congrats Wimbledon & U.S. Open ladies doubles & mixed doubles champion Martina Hingis :).
Always such a joy to watch.
It doesn't get better than that!. Way to finish off the Grand Slam season!.