Borrello scored early in a first half which was dominated by the home side, but it was Adelaide who had the better of the second 45 minutes.
But Brisbane, who were under the pump, put the game to bed courtesy of Maclaren's third goal of the season.
Springing the offside trap, Maclaren raced clear of the labouring Adelaide defence.
He looked to have taken too many touches and just when the chance appeared to have gone, Maclaren cut in from the right, and curled a beauty of a left footer past the diving John Hall.
Borrello then raced clear in added time to add the third.
But Adelaide had started the match on the front foot and Cirio forced Jamie Young, again deputising for Michael Theo, into a save.
Maclaren then forced Hall into a save, but there wasn't much the giant Adelaide keeper could do about Borrello's goal.
A delightful pass from Matt McKay picked out Thomas Broich, and his first time ball back into the area pinged around before dropping perfectly for Borrello.
Hall got hands to the shot, but it was struck too well and from too close for him to keep it out.
It was the cue for Brisbane to dominate the first half.
Borrello tore away down the right and tried to square to Maclaren, only for Tarek Elrich to slide in and make a goal-saving block.
Broich then sliced open the Adelaide defence with a perfect pass. Maclaren's first touch was immaculate, and only a sharp save by Hall denied him.
The Reds couldn't find the answers and it was only in the dying minutes of the half that they found an attacking threat.
A wonderful pass by Marcelo Carrusca released Craig Goodwin, but his right footed shot, although firmly struck, was too close to Young.
Then, Elrich screwed a shot wide as Adelaide gave themselves some hope leading into the break.
The second half was a completely different story.
Adelaide finally showed what they were made of, and with Brisbane sitting deep it seemed only a matter of time before they would equalise.
Indeed they probably should have when Cirio was one-on-one with Young shortly before the hour mark, but the Brisbane 'keeper made a tremendous one handed save to help the ball over the bar.
Young looked no chance as Cirio bore down on him, leaving Jade North behind in the process. But just as Cirio was ready to celebrate, Young thrust up a left paw to somehow divert the ball to safety.
Maclaren was always in the game, even with Brisbane sitting deep, and he lashed a shot againt the crossbar to remind Adelaide to keep an eye on him.
But the Reds were more concerned with scoring a goal of their own, and they inched closer and closer.
Isais shot over the bar when he should have been more composed, and then Daniel Bowles made a superb sliding block to shop Elrich, who had burst into the area.
Maclaren then popped up with his fantastic goal, and when McKay released Borrello in stoppage time, the young striker made no mistake.
Roar coach John Aloisi hailed the impact of Borrello, who he tipped during pre-season would start hitting the back of the net with regularity.
"I think he's got goals in him," Aloisi said.
"If he keeps on persisting and making those runs, he's going to hurt the opposition.
"He's quick, Brandon, but it wasn't just his pace that hurt them tonight. It was his timing."
Adelaide boss Guillermo Amor was very happy with his players, insisting that they carried out United's game plan well and did everything, except score.
"They did what we told them to do and, at the end, the result didn't go with us. It's football," he said.
"We're working a lot on this, every day. Today, it didn't go in but maybe they will go in next time.
"When you work more and more, that's when things go better for you."
Brisbane Roar 3 (Borrello 9', 90+3', Maclaren 79')
Adelaide United 0
Suncorp Stadium, Brisbane
Referee: Chris Beath
Crowd: 10,707
Suncorp Stadium, Brisbane
Referee: Chris Beath
Crowd: 10,707
