"As of right now, this very moment, Jim is DONE with chemotherapy!" Kelly's wife, Jill, posted Tuesday on Instagram.
She noted that he has four radiation treatments to go at Erie County Medical Center in Buffalo. He received the early part of his radiation and chemotherapy at Lenox Hill Hospital in New York City before coming home to Western New York for the remainder of his treatments.
"Keep those prayers coming," he said a video message earlier this month. "I sure need them. Without you I wouldn't be able to get through this. God bless you."
Kelly was originally diagnosed with oral cancer in June 2013. After the diagnosis, he underwent surgery to have part of his upper jaw removed. The surgery was considered a success and for over nine months, Kelly appeared to be cancer-free.
The 54-year-old then found out in March that the cancer had returned, which led to the chemotherapy treatments that Kelly began on April 6.
Kelly, who led the Bills to four Super Bowls in the 1990s, was inducted into the Pro Football Hall of Fame in 2001.