The 71-year-old 18-time grand slam singles champion has decided to step back from her professional commitments, including Wimbledon next week, as she seeks treatment, including chemotherapy.
Evert was diagnosed for the first time in December 2021 following a preventative hysterectomy after she had been informed she was at risk of cancer.
On Thursday, she wrote on Instagram: "I have always believed in being open and honest about my health journey.
"This past weekend, after undergoing CT and PET scans, I learned my ovarian cancer has returned.
"I have already undergone surgery as the first step in my treatment and recovery, and will begin chemotherapy in the coming weeks.
"Because of this, I will not be attending Wimbledon this year, and I will step back from my professional commitments over the next few months to focus on my health.
"Ovarian cancer is relentless, but I will stay optimistic and determined in continuing to fight this battle.
"I am deeply grateful to my medical team, my family, friends and everyone who has reached out with kindness and encouragement.
"I look forward to seeing everyone very soon."
Evert's younger sister, Jeanne, died of the same disease in 2020 but the family were initially informed that genetic testing had not flagged up anything sinister.
But further research led to advancements in the field and Evert was advised in October 2021 to seek more information about her own situation.
A blood test showed she, too, had a pathogenic variant of the gene, which led to the hysterectomy and the discovery of a tumour.
In December 2023, Evert shared that her cancer had come back. In that update, Evert revealed that doctors at that time also performed surgery while the athlete also underwent chemotherapy.
Messages of support immediately arrived on social media on Thursday, with Evert's long-time rival and friend Martina Navratilova writing: "My friend Chrissie is a champion of champions and as such she will slay this monster again.
"We are all pulling for you, and know you will come out on the other side cancer free again."