Mulvey was named interim coach in December when Rado Vidosic stepped aside to become the club's technical director just 11 games into the 2012-13 season.
The Roar officially announced they would retain Mulvey in Brisbane on Friday as the team returned from Thailand after losing their Asian Champions League qualifier against Buriram United in a penalty shootout.
It added to a frustrating run for the Roar who are third-last on the A-League ladder but one win outside the top six.
However, Mulvey had done enough to convince the club's board - who met on Thursday just hours after their ACL failure - that he should retain the reins fulltime.
"It's always nice to announce something like this on the back of a win," Roar general manager Sean Dobson said.
"But I think if you actually realised what Mike has achieved behind the scenes in the dressing room and the way he has scouted players, what he is doing in terms of bringing leadership structure and actually providing a really strong vision for the club - there is a lot of good work there.
"The owners believed it was time to bring that stability to the group."
Mulvey said he was "thrilled" with the appointment.
But he would not be drawn on whether he was surprised by the timing of the decision after a "bitterly disappointing" ACL failure.
"But if I am truly honest with myself we are probably not equipped well enough to compete deep into the (ACL) tournament this year in terms of our depth," Mulvey said.
"I will be the first to admit the results are not perfect.
"The truth of the matter is we haven't quite reached our (expected) levels this season for one reason or another.
"I don't want to go into those reasons. But they will be addressed and there will be changes made."