Co-owner John Mara of the NFL franchise New York Giants has now made his cancer diagnosis public.

On Monday, John Mara, co-owner of the NFL franchise New York Giants, announced that he had recently been diagnosed with cancer. The franchise’s statement does not specify the type of cancer Mara has.

Despite his illness and the cancer treatment that will now follow, the 70-year-old said he intends to remain active in the Giants organization.

“I feel strong and optimistic and am determined to bring this to a positive conclusion,” Mara said in a statement released by the Giants. “I plan to remain actively involved with the team throughout my treatment and am fortunate to have incredible support—personally, professionally, and medically.”

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— New York Giants (@Giants) September 29, 2025

Mara has been responsible for the Giants’ operational organization for years. He holds a 50 percent stake in the Giants, with the other half owned by Steve Tisch.

Mara and Tisch are the two owners who took over ownership of the New York NFL franchise from their respective fathers, Wellington Mara and Bob Tisch. The franchise was founded in 1925 by Mara’s grandfather, Tim. John Mara has been with the Giants for 34 years. The lawyer is also chairman of the NFL Management Council and a member of the league’s Competition Committee.