Panthers coach Kevin Dineen made the announcement after Florida's morning skate, saying Theodore "deserves the start if he can go."
Theodore missed Game 6 on Tuesday with an unspecified injury after shutting out the Devils in Game 5. Theodore was able to go through an on-ice workout on Wednesday, saying afterward that his condition was improving.
Theodore is 2-1 with a 2.60 goals-against average in the series against the Devils, stopping 92 percent of the shots he's faced.
It's only the second Game 7 in Panthers history. Florida won at Pittsburgh to wrap up the 1996 Eastern Conference finals.