‘The Wizard’, who recently won his first major title when he was crowned European Champion in Germany, triumphed 6-1 against Nicholson to clinch the £15,000 first prize.
The world number six, who had seen off Per Laursen and Alan Tabern to reach Sunday’s last 16, began the day with a 6-1 victory over Ian White.
He then saw off Johnny Haines 6-2, before producing a brilliant semi-final performance to beat Kim Huybrechts 6-1.
Whitlock then made sure he claimed his third PDC title in less than two months, when he defeated ‘The Asset’ by the same scoreline.
“It feels fantastic and I’m over the moon to win,” Whitlock told the PDC’s official website.
“It’s brilliant for two Australians to be in the final and Paul’s done really well this weekend.
“I seem to perform well on the Continent and to follow up the European Championship win with this is great.
“I can’t wait for the World Championship now and hopefully I’ll be holding the trophy at the end of that too!
“Paul’s a very good friend of mine and we’re World Cup pairs partners, so it was tough playing him and I’m just happy to get the win.”
Nicholson, who was competing in the final day of a European Tour event for the first time, kicked off his Sunday with a 6-1 success over Max Hopp in the last 16, having beaten Ross Smith and Michael van Gerwen to reach that stage.
The 2010 Players Championship Finals winner saw off Arron Monk, who reached his first European Tour quarter-final, before producing a fabulous display to defeat Wayne Jones in the semis, with the aid of a 101.02 average.
Nicholson said: “It’s been a huge weekend for me. This year has been up and down but this weekend has proved to me that all the hard work really has been worth it.
“I’ve had some really tough games and played some great darts. By the time the final came around I was shattered and ran out of steam but Simon’s been used to getting this far in tournaments this year and I haven’t. He’s had a bit more darts fitness than me and I give him all the credit.
“I’m so privileged to have been part of the first all-Aussie final on the Pro Tour and I’m proud of myself to have got this far. Before this week, nobody had any expectation of me and I’m thrilled to have been in the final.”
By Chris Murphy
Images courtesy of Lawrence Lustig/PDC