The Socceroos booked their spot in the decider with a hard-earned 2-0 win over UAE in Tuesday's semi-final at a wet Hunter Stadium.
Korea, who beat the Socceroos in the group stage just 10 days ago, now stand between Australia and their first major piece of silverware.
"It's a massive game. We made the final four years ago as well which was great for our nation but we've now been in Asia for a little while and we haven't won anything in the men's game yet," Postecoglou said.
"This gives us an opportunity at a national level anyway to achieve something. It will be a big game, a sold out final, in a major tournament and we're not going to host another one in our lifetime which is why it's important for us.
"It's been an outstanding tournament and great for our game and I think it would have put a dampener on it if we weren't in the final.
"For us to be there is a great way to end up what's going to be a fantastic tournament. You can always dream, if we win it, it will be one of the biggest games ever for our code and our country.
"But we've still got some steps to go first."
The major step will be breaching a Korean defence that has yet to concede in five games this tournament and will have the benefit of an extra day's rest and recovery under their belt.
But with a sell-out crowd expect at ANZ Stadium, the Socceroos boss hopes it will drive his side to find something more and give him one more big performance.
"It will make a difference for sure," he added. "To get into a final you put a lot of effort into it and again it will come down to moments in the game.
"If we have an 80,000 strong crowd behind us they can generate the kind of energy we need.
"It's fantastic. The Australian sporting public has really embraced the team, they've enjoyed the way we've played our football, and are really supporting the team.
"That's generated a real good vibe around and the players can feel it, hopefully that can continue on Saturday."
