The former Socceroos striker revealed Postecoglou played a major role in his coaching development since he was sacked as Melbourne Heart coach in December 2013.
"He's been not only just recently, but since I left Melbourne Heart or was dismissed from there, I've sat down with Ange," Aloisi told reporters on Friday in his first official capacity as Roar coach.
"He was also helping me in actually making sure I was ready for my next move.
"He's a great person to fall back on.
"Who else to ask other than Ange, that knows this club inside-out and knows this group of players inside-out?"
Postecoglou also helped convince Roar that Aloisi was the right man for the job, with his recommendation to departing chairman Chris Fong helping seal Aloisi's two-year coaching contract.
Aloisi said it is normal that some Roar fans are unhappy with his appointment but believes he is well-equipped to prove them wrong.
"If I was worried about what people would say ... I would have stayed in the media," he said.
"It was my first job as a head coach and you learn from mistakes that you make.
"But you probably learn sometimes when you're not successful, because you have to look back and see what you didn't do so well.
Having also spent time studying the methods of overseas clubs - including Catalan giant Barcelona- since he was axed by Heart, Aloisi feels he has much more to offer as a coach.
"One of the great things I saw at Barcelona was how the club still gets the best out of players who have won everything," Aloisi said.
"I see parallels at the Roar as they have won a lot of silverware in recent seasons and now the challenge is for us to aspire to new heights in season 2015/16 and beyond as we reaffirm our standing as Australia's premier football club."
Aloisi, 39, will relocate to Brisbane next week and attend Roar's exhibition game against La Liga outfit Villarreal on Wednesday 3 June - interim coach Frans Thijssen's last game in charge - before he gets to work full-time ahead of the Friday 17 July clash with the Reds.
He is comfortable with the Roar squad he has inherited but will look at adding some quality before the start of the next A-League campaign.
"Our player list is pretty full right now but I will be looking over the coming weeks to see what players are around who could bring something extra to what already is a very talented squad," Aloisi said.
Chairman Chris Fong, who will soon step down from that role, said Aloisi would be responsible for the club's entire football operations.
"John brings to the club a life-long passion for football and a fresh hunger for success," Fong said.
"We have begun rebuilding the club and having John on board now ensures we can maximise the off-season as we set our targets for season 2015/16 across all competitions in which the Roar participates.
