The former world No 1 golfer and the Olympic skiing champion blamed the pressure of their busy schedules for the split.
Lindsey Vonn said on Facebook that the decision was mutual.
In a statement on his website, Tiger Woods said he would “always cherish our time together”.
Tiger Woods and Lindsey Vonn first publicly announced they were an item in March 2013 following weeks of speculation.
“After nearly three years together, Tiger and I have mutually decided to end our relationship,” Lindsey Vonn, 30, said on her Facebook page.
“I will always cherish the memories that we’ve created together. Unfortunately, we both lead incredibly hectic lives that force us to spend a majority of our time apart.
“He and his beautiful family will always hold a special place in my heart.”
The couple were last seen together in public at last month’s Masters golf tournament, where Linsey Vonn was with Tiger Woods’s 7-year-old daughter Sam and 6-year-old son Charlie.
Tiger Woods, 39, said in his statement: “I have great admiration, respect and love for Lindsey and I’ll always cherish our time together. She has been amazing with Sam and Charlie and my entire family.
“Unfortunately, we lead very hectic lives and are both competing in demanding sports. It’s difficult to spend time together.”
Tiger Woods was previously married to Swedish model Elin Nordegren, but they divorced in 2010 after it emerged the golfer had had a series of extramarital affairs.
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