Schilling, who was tapped in December to be part of ESPN's "Sunday Night Baseball" broadcast team for the upcoming season, revealed the news in a statement released through the broadcaster.
"I've always believed life is about embracing the gifts and rising up to meet the challenges," Schilling said. "We've been presented with another challenge, as I've recently been diagnosed with cancer."
His wife Shonda Schilling also has had a bout with cancer -- she was diagnosed with stage 2 malignant melanoma in 2001.
The 47-year-old, known for his clutch performances in the post-season, did not specify what type of cancer he was diagnosed with.
He asked fans to "keep the Schilling family in your prayers."
"With my incredibly talented medical team, I'm ready to try and win another big game," he said.
"Our thoughts are with Curt and his family during this challenging time," the network said in a statement.
Schilling pitched 20 years in the major leagues, compiling an 11-2 record with four complete games and a 2.23 ERA in 19 playoff starts. He won two World Series with the Red Sox and another with the Diamondbacks.