Ibini's powerful strike early in the fist half put Sydney in front before Brosque extended the lead on the stroke of half-time with a stunning improvised effort.
The win was virtually sealed immediately after the break as Brosque bagged his second, with Craig Goodwin's fine individual effort coming too late for Adelaide.
Naumoff made absolutely sure of the win with a goal in stoppage time after a being teed up by substitute Terry Antonis.
Ske Blues' players and fans were left to celebrate the 4-1 triumph that books them a place against rival Melbourne Victory at AAMI Park next weekend.
Sydney welcomed back Marc Janko up front and Sebastian Ryall in defence, while Adelaide was unchanged from the eleven that defeated Brisbane Roar in the elimination final.
In front of 26,783 passionate fans, the home side started brightly and inside 10 minutes Naumoff dribbled from just inside the Reds half, ran at the opposing defence and curled a short just wide of the post.
On 18 minutes, Milos Dimitrijevic played it down the line for Naumoff who burst into the area and pulled the ball back. It fell into the path of Ibini on the edge of the box and he hammered a shot into the top corner to make it 1-0 for Sydney.
Adelaide came close to hitting back in the 25th minute when Jimmy Jeggo played a delightful ball through to Sergio Cirio, who found himself one-on-one with Vedran Janjetovic. But under pressure from Sky Blues defenders Cirio couldn't find a way past the host's goalkeeper.
The Reds came close again before the half hour after they earned a free kick just outside the area. Pablo Sanchez curled in a delightful effort that struck the crossbar.
On the stroke of half-time Janjetovic was forced into another save as Isaias let fly from distance and the Sky Blues shot-stopper palmed away.
Yet only seconds later Sydney doubled its lead. Ibini found himself with space near the box and crossed in for Brosque who, with a delightful backheel, got the better of Galekovic to extend the host's advantage to 2-0 at the break.
Reds boss Jose Gombau brought on exciting winger Awer Mabil for defender Osama Malik at the start of the second half.
But any hope of an Adelaide fightback evaporated in the 47th minute as Naumoff found Janko, who appeared to be offside and a deflection fell straight to Brosque in front of goal. The in-form striker blasted in to make it 3-0 and all but book Sydney's place in the grand final.
The visitor continued to fight and approaching the hour Marcelo Carrusca sent a shot from distance that whistled wide of the Sky Blues' post.
At the other Sydney was on the verge of making absolutely sure when Brosque crossed in for Janko near the penalty spot. Yet the incredible reflexes of Galekovic denied the Austrian.
Adelaide did give itself feint hope 15 minutes from time. Goodwin picked up the ball inside his own half and dribbled all the way into the host's penalty area before squeezing a shot that got the better of Janjetovic and made it 3-1.
It set up a tense final stage of the encounter, with the Reds coming close on a number of occasions, but the Sydney defence held.
In stoppage time Naumoff played a one-two with Antonis before hitting a shot past Galekovic to secure the 4-1 win.
Last time the two teams met Galekovic pulled off nine saves to almost single-handedly thwart Sydney's rampant attack and Sky Blues coach Graham Arnold said that was one main difference this time.
"Eugene Galekovic didn't play the way he did a few weeks ago," he said.
"He wasn't given a chance to because we didn't hit him. This time we missed him and the balls went in the back of the net.
"Some of our play was very good.
"To go in at 2-0 at half-time was a perfect scenario and with that forced Josep to change the system at half-time... then scoring after half time was perfect time to score goals.
"I said to the players 'we couldn't be prouder of what we've done but we've won nothing. Enjoy tonight and enjoy tomorrow but Monday we're back in at work and we've got a hell of a challenge ahead of us to go to AAMI (Park)'."
Gombau said despite the loss he was still happy with his side's spirited performance.
"We had many, many chances and we just scored one goal," he said.
"Football is to put the ball in the net and they (Sydney) did.
"I am satisfied with the job they did. I am happy with the way they fight and run down every single ball.
"There is always a winner and a loser and today it is our turn to be the loser and we have to be a good loser."