Cook County Sheriff Tom Dart told the Chicago Tribune the Rev. Daniel Mallette, pastor emeritus of St. Margaret of Scotland Church, suffered broken ribs and a swollen face from the beating.
"It was a very vicious attack," said Dart, a parishioner of Mallette's church.
Preliminary reports indicated Mallette awoke about 12:30 a.m. to find two men in his bedroom demanding money.
When the elderly priest failed to move fast enough, the men beat him before fleeing with an unknown amount of cash.
Mallette has long been a fixture at the church, presiding over a diverse congregation and providing outreach to poorer pockets of the community.
Officials at the Chicago Archdiocese could not be reached for comment, the Tribune said.