Two months after rumors began circulating, Woods and Vonn posted announced the relationship with photos on their Facebook pages.
"This season has been great so far and I'm happy with my wins at Torrey and Doral," Woods said. "Something nice that's happened off the course was meeting Lindsey Vonn."
The golf superstar went on to say that he and the ski champion have been friends for some time, but it recently developed into a romantic relationship.
Woods, 37, made a stop in Austria - where Vonn was competing in the Alpine skiing world championships - in January on his way to Abu Dhabi to start his season. Two weeks ago, after he won the Cadillac Championship at Doral for his second win this year, The Daily Mail published photos that showed a woman, who appeared to be Vonn, in a golf cart at the marina where Woods' yacht "Privacy" was docked.
"I guess it wasn't a well-kept secret but yes, I am dating Tiger Woods," Vonn joked on her Facebook page.
Woods' marriage with Elin Nordegren collapsed in 2010 after revelations of multiple extramarital affairs. Vonn is recently divorced.
The Associated Press contributed to this report.