At 46 years and 324 days old, Navratilova would have beaten the record of Margaret Osborne Dupont -- who won the U.S. mixed crown aged 42 years and 166 days in 1960 -- had she won.
But under cloudless skies on the Arthur Ashe stadium court the American winner of a record 171 doubles and 166 singles titles and her Russian partner were outplayed by the defending champions.
"They never really let us into the match. We tried our best and it is just a great bonus to be here," Navratilova said.
"If you guys have anything to do with it then I guess I will be back," she told the cheering crowd.
Navratilova and 18-year-old Kuznetsova shared a runners-up prize of $200,000
Ruano Pascual and Suarez picked up $400,000.
Having lost in the final at the last three grand slams this year, the Spanish-Argentine pairing were relieved to win.
"We really wanted to win one this year," Ruano Pascual smiled. "We played very good today, one of the best matches these two weeks."
Navratilova first played at the U.S. Open 30 years ago. She won the doubles title here on six occasions, with Pam Shriver in 1983, 1984, 1986 and 1987, with Hana Mandlikova in 1989 and with Gigi Fernandez in 1990.
She also won four U.S. singles titles in 1983, 1984, 1986 and 1987.
This year, as a doubles player only, she has won five titles and with her mixed doubles wins at the Australian Open and Wimbledon with Leander Paes became the oldest player to win any grand slam title.