Mulvey parted ways with Roar in November, just months after leading the Brisbane outfit to the 2013/2014 A-League Championship.
The 52-year-old saw his time at the A-League franchise end after a disagreement regarding football philosophies, with some labelling Mulvey the victim of a 'backroom power play'.
Mulvey had initial said that he would spend the year that followed honing his technical skills, and is believed to have turned down a number of opportunities to return to coaching.
However, the Manchester-born tactician says that the chance to work in Sabah was too good to say no to – although he initially did just that.
"It's not often you get given an opportunity where you can give back to football in our region – which they most certainly are – and this was something I may not get to do again," he told the Brisbane Times.
"I feel like it's a project where I can come in, work with the local coaches and players and provide them with some of the knowledge and insight from the A-League level, giving them something to work with going forward.
"Sabah is a rich football region and while they've had some success in the past, they realised the need for some assistance to steer the club back on track."
He added: "They came back to me again and again and eventually the region's sports minister asked me to get involved.
"I could see their passion and vision was very much about restoring their club to what it was in the mid-1990s [winning the Malaysian Super League in 1995 and the Malaysian FA Cup in 1996].
"Other clubs are spending huge amounts to get ahead in Malaysia but I think we can find an edge in terms of preparation, performance and professionalism."