Moore is reunited with Rovers boss and ex-Baggies team-mate Michael Appleton.
The 38-year-old is joined on Rovers' backroom staff by head of senior recruitment Luke Dowling and head of sports science Chris Neville, who have left their roles at Appleton's former club Portsmouth.
"When the gaffer asked me to come up here and be part of his staff, I was really excited and I can't wait to get started," Moore told Blackburn's official website.
"We were team-mates together at West Bromwich Albion and after sustaining an injury early in his career, the gaffer started to pick up his coaching credentials and setting the foundations to be a really top coach and manager now."
"My career continued, but we've always kept that friendship going and it's presented itself where we find ourselves working together and I'm really looking forward to working alongside him and the challenges that lie ahead.
"He's someone that I've believed in from day one. He's got excellent tactical awareness for the game and his all-round manner is perfect for the football club. I've seen it first hand and I'm just really looking forward to working alongside him and the rest of the staff and bringing some good times back here to Blackburn Rovers."
Appleton added: "I'm delighted to welcome Chris, Luke and Darren to the club. I feel like we have put together a strong backroom team to add to the fantastic staff already in place.
"They all have a great work ethic and professionalism and can't wait to get started. I am confident they will bring a lot to the club."