Freeney, the three-time Pro Bowler, is the highest-paid defensive player in the NFL. He injured his left foot in Sunday's 23-21 loss to San Diego and was scheduled to undergo surgery later this week or early next week.
The blow is potentially devastating to Indianapolis, which has already been depleted by injuries. Seven starters missed Sunday's game, and Indianapolis lost four more starters, including Freeney, during the game.
"Dwight is a player you cannot replace," former Pro Bowl safety Bob Sanders said. "But we'll continue to move on, continue to get better. We'll put new guys in and continue to roll. That's what Dwight would want us to do."
The Colts (7-2) don't have a choice.
Freeney injured the foot while making one of his patented spin moves on a pass rush. He immediately crumpled to the ground, hopped off the field and then could not put any weight on the foot while standing on the sideline. Eventually, he was taken to the locker room on a cart.
In a statement the Colts said Freeney was expected to make a full recovery in time for next season.
To help fill the void, the AFC South-leading Colts claimed Simeon Rice, a two-time All-Pro defensive end, off waivers on Monday. Rice spent the first half of the season with Denver, which signed him to a one-year, $3 million (2 million EUR) contract in September.
Rice's transition should not be difficult because he spent six seasons in Tampa Bay, where he played in the same system used by the Colts. Rice is also familiar with Colts coach Tony Dungy, who helped persuade Rice to join the Buccaneers in 2001.