Speaking to People, Navratilova confirmed that she has now successfully completed her course of treatment.
"I am cancer-free," she stated. "Technically I was cancer-free after the lumpectomy in March… But then I had radiation to make sure that it killed any cancer cells that were still hovering about."
The former professional tennis player admitted that her radiation sessions proved to be more daunting than she had originally imagined.
"Surgery was easy, but the radiation was trickier. It was six weeks of really low energy. Radiation just sucks your energy like a vampire, day by day."
She continued: "Even when it was over, it took it a long time to get my energy back up… But now I feel as good as new. I have an excellent prognosis, and I'm really doing well."
Beating cancer has inspired the athlete to make some changes in her everyday life, she added.
"I stopped drinking coffee. It has already made me feel better. But other than that, I've always been very healthy."