The highly-rated 43-year-old famously coached Pontypridd to a first cup and league double in 2012/13 after securing a Principality Premiership League title in 2012 and a Swalec Cup victory in 2011.
He became a WRU Development Officer after retiring as a player and refined his coaching skills within the union's pathway structure. McIntosh was appointed forwards coach to the Wales Under-18 squad in 2008 and continued to work within the international age grade structure.
A cult hero during his playing days, McIntosh played more than 450 times for Pontypridd and won two senior Wales caps as a back row forward.
McIntosh has a held a part-time coaching advisory role with the Blues this season, but has now been appointed on a full-time basis to the delight of Director of Rugby Phil Davies.
"Dale and I go back a long way from our playing days and I have huge respect for him as a man and rugby person," said Davies.
"He has been a simply phenomenal servant for Pontypridd. They are a great club and, along with Cardiff RFC, are a great credit to our region.
"Dale has done a fantastic job for Pontpridd, as a player and coach, and has also been successful as part of the Wales Under-18 set-up. His pedigree as a rugby man, player and coach is outstanding.
"When I first arrived at Blues last year I wanted him involved," added Davies. "At that stage it wasn't possible, but over the course of the last 18 months we have kept in touch through his role in the region and he has been involved with us from the summer.
"We are very grateful to the WRU and Pontypridd for releasing him to become Defence Coach with us on a full-time basis."
"I would also like to thank Rob Powell for his contribution to Blues. He joined us to work alongside Xavier Rush last season and has continued to work hard for us this season. We wish him every success for the future."
WRU Head of Rugby, Josh Lewsey, added: "Dale has developed excellent coaching skills within the WRU structure since his retirement as a player.
"He was a player of great talent and has put his rugby knowledge and experience to excellent use while developing his coaching skills through the WRU regional and international age grade system and the Principality Premiership."