The Broncos activated Reid (hamstring) to the 53-man roster from injured reserve Tuesday, Aric DiLalla of the team's official site reports.
Reid had been a full participant in practice the last three weeks, so had he not been activated Tuesday his 21-day window would have expired, causing him to revert to season-ending IR. Instead, the undrafted rookie will stand to handle a role on special teams during the postseason, beginning in the AFC divisional round.