The naturalised American teamed up with Leander Paes to win the Australian Open mixed doubles titles, beating Todd Woodbridge and Eleni Daniilidou 6-4 7-5 for the one grand slam title to have eluded her.
Aged 46 years and three months, she also became the oldest grand slam champion in the sport's history, eclipsing Norman Brookes. The Australian won the men's doubles here in 1924 aged one month younger.
Navratilova easily beat the next oldest woman, Margaret DuPont, who was 44 when she won the 1962 Wimbledon mixed doubles.
As Woodbridge hit the net on match point after 97 gut- wrenching minutes on centre court, Navratilova screamed "yes", raised her eyes to the heavens and skipped on the spot.
She took off her spectacles and embraced her Indian partner before hugging Woodbridge, her mixed partner at Wimbledon last year.
The crowd gave her a standing ovation after she matched the feat of Australian great Margaret Court, who completed a sweep of titles at all the slams in the 1960s before tennis turned professional.
Navratilova's 57 grand slam titles place her second on the all-time list behind Court with 62.
MOCK AWE
Navratilova bounced on the spot and chatted to Australian Open tournament director Paul McNamee, her partner when she won the Wimbledon mixed in 1985.
Paes bowed and scraped in mock awe before the American as Navratilova soaked up the atmosphere.
As a Czech, Navratilova partnered Ivan Molina to the mixed doubles title at the French Open in 1974. Between then and her retirement from the sport 20 years later in 1994, she garnered an extraordinary 56 grand slam titles -- 18 singles, 31 women's doubles and seven of the mixed variety.
Those 56 included a full set of singles, doubles and mixed at the French Open, Wimbledon and the U.S. Open.
When she lost to Jim Pugh and Jana Novotna in the final in Melbourne back in 1988, she could have been forgiven for thinking it was a set she would never complete.
She visited Australia for the last time in 1989 and retired from the sport five years later.
She returned in 2000 to play occasional doubles, however, although her return to Melbourne this year after a 14-year absence was regarded by many as a capricious notion, something of a sideshow at the first grand slam of the year.
It turned out, however, to be one of the best decisions of her life.
