McDermott had a hugely successful spell in charge of the Rhinos.
McDermott guided the Rhinos to the Super League title in 2011, 2012, 2015 and 2017, the 2012 World Club Challenge and two Challenge Cup triumphs before being sacked in July 2018 after a poor run of results.
He went on to coach Toronto Wolfpack until they pulled out of Super League in the summer of 2020 and ended the 2021 season as a consultant with relegated Championship club Oldham.
Rovers chairman Mark Campbell said: “I’ve made it really clear in my tenure at the club that I’m committed to giving everything I possibly can to bring Super League status to this club, it is what this club deserves.
“I’ve known and worked with Brian previously and I know he is the right fit for this club to take us to the next level.
“We have moved quickly to take this opportunity; it is not every day you get the chance to bring a top-class coach like Brian to your club and we are extremely excited about working together moving forward.”
Featherstone missed the chance to secure a Super League spot on October 10, losing to Toulouse in the Million Pound Game.