The fourth seeded Indo-Swiss pair on Friday defeated unseeded Americans Bethanie Mattek-Sands and Sam Querrey 6-4, 3-6, 10-7 in a tricky final in one hour and 17 minutes on Friday to win their third Major title together this season.
The duo had earlier won the Australian Open and Wimbledon crown.
The Indian-Swiss pair fired 32 winners and staved off four of five break points over the 77-minute affair.
They rallied from an early 4-1 deficit in the match tie-break, claiming nine of the next 12 points to prevail.
With the mixed double win, 42-year-old Paes surpassed compatriot and former partner Mahesh Bhupathi's record of eight mixed doubles titles.
Paes in his 17 Slam record, have won eight men's doubles and nine mixed doubles title.