The drama pilot, which focuses on a team of firefighters in the 'Windy City', will be executive produced by Law & Order's Dick Wolf.
Walker will play Chief Walter Boden, an amateur boxing champion who is considering retirement, according to Deadline.
The English actor is known for appearing on HBO drama Oz between 1997 and 2003 and also starred in 2010's short-lived ABC legal drama The Whole Truth.
Last year, he was attached to NBC fantasy pilot 17th Precinct, but the project was not picked up to series.
Derek Haas and Michael Brandt have written the Chicago Fire pilot, which will be directed by Jeffrey Nachmanoff.
NBC has picked up a number of other drama pilots, including medical pilot County and Jekyll and Hyde update Do No Harm.
The network has also ordered a full 13 episodes of Bryan Fuller's Hannibal, based on the character of cannibalistic serial killer Hannibal Lecter.
> Bridget Regan, Being Human star join NBC's The Frontier