Pope Francis, 86, will have surgery on his abdomen on Wednesday afternoon at Rome's Gemelli hospital, the Vatican said in a statement.
It added that his medical team had decided in recent days that surgery was required and that he was expected to stay in hospital for "several days" to recover.
He will have the operation on his abdominal wall under a general anesthetic, the Vatican said.
Francis was due to be taken to hospital following his weekly audience at the Vatican on Wednesday morning, where he made no mention of the planned operation. He had spent 40 minutes having a check-up at Gemelli hospital on Tuesday.
The pope, who marked the 10th anniversary of his pontificate in March, often uses a wheelchair or a cane to walk because of persistent knee pain.
In July 2021 he had part of his colon removed in an operation aimed at addressing a painful bowel condition called diverticulitis. He said earlier this year that the condition had returned.
The pope last year said he didn't want to have an operation on his knee because the general anesthesia for his colon surgery had brought disagreeable side-effects.