Mike Mulvey's side will face the winner of Sunday's other semi-final between Perth Glory Youth and Adelaide United Youth in the season showpiece next weekend.

Their appearance on the Grand Final stage is just reward for a campaign full of spirit, character and quality, epitomised in this semi-final triumph over the NYL Premiers.

Gold Coast got off to a dream start, taking a two-goal lead inside the opening four minutes.

First to strike was local defender Ben Wearing, who rose at the far post to head home Koh Satake's corner and set United on their way with less than 60 seconds on the clock.

Fortune played a part in United's second goal, but it was no less than their positive early approach deserved.

Ben Halloran was the architect, his weaving run past three defenders opened up space for a shot and a wicked deflection helped the ball on its way into the net.

United continued to dominate and were unlucky not to add to their tally as they pressed to kill the game as a contest before the break.

But the tension grew before half-time when Zac Anderson was penalised for a foul in the penalty area. Mariners' skipper Panny Nikas converted the resulting spot-kick to reduce the deficit and put his side firmly back in the match.

The second period was end-to-end action, typical of a sudden death encounter, but Gold Coast put the result beyond doubt in the 83rd minute.

Tahj Minniecon's fine work on the right-hand side set Chris Harold free and the young striker bore down on goal before clipping the ball expertly over Mariners' ‘keeper Matthew Ryan.

It was Harold's 15th goal of a highly impressive campaign, but he will score few more important goals in his career with this strike ending the Mariners' hopes of a comeback.

After watching his team advance to the National Youth League Grand Final in their first season, Youth Head Coach, Mike Mulvey, said he couldn't be prouder of his young troops.

"All season they have worked hard and tried to play the attacking football we've asked of them - I'm really proud of them," Mulvey said.

"We started well, which we haven't always done in recent times, and our players have learned a lot today. They stood up in a difficult and important game, against a good side, and there were some outstanding individual performances.

"When everyone pulls together like they did today something special can happen and we fully deserved our win.

"Getting to the Grand Final is the reward they deserve, but the job isn't done yet. Now that we're there we want to bring the trophy home to the Gold Coast."