Navratilova, who stopped playing in singles matches in 1994, is competing in both women's and mixed doubles at Wimbledon this year.
She is teamed with Liz Huber in the ladies' doubles and Mark Knowles in the mixed doubles.
"The decision that this is my last year, that is a definite," Navratilova said Tuesday after advancing to the fourth round of women's doubles. "The body's great. I probably could do it another five years if I wanted to, but I don't want to. I'll miss the competition. I want to move on to my next life."
Navratilova, who turns 50 in October, has been a member of the WTA for 33 years, and has 58 Grand Slam titles.
When she quit playing singles, she had 167 singles titles and was ranked No. 1 in women's tennis for 331 weeks.