The Dutchman, who won Players Championship 21 earlier in the week, produced another dominant display to secure his eighth ranking title of 2026 and become the first player this year to win multiple European Tour events.
Cross averaged more than 102 in a high-quality final, but was unable to cope with Nijman's scoring power. The 25-year-old won four consecutive legs to establish control of the contest before closing out victory with a 103.80 average.
“I cannot put this into words. It’s so amazing,” Nijman said after lifting the trophy.
“Sometimes you have those days where you feel this can be a winning day because you feel so confident and today was a day like that.
“I’m really happy I did it. It was so warm up here, so it was a game of stamina, but whenever you get control, you’re probably going to win the game, and that’s what I did.”
Nijman's route to the title included victories over Stephen Bunting and Mike De Decker, before surviving a semi-final scare against Ross Smith.
“This tournament just shows the level of darts at the moment,” Nijman said.
“Even without Luke Littler and Luke Humphries, the level is still high and that’s what the PDC is like now.
“I’m really looking forward to the World Matchplay. Last year I was there and I felt this was the best tournament there is.
“I hope I can do some damage there and show the darts I’ve been producing here, and we’ll just see what happens.”
Cross, meanwhile, continued an encouraging week after clinching Players Championship 22. He reached his first final on the European Tour in more than two years with wins over Gian van Veen, Kevin Doets, Nathan Aspinall and Tom Sykes.
“Wessel played great there,” Cross said.
“I don’t enjoy the heat, but the crowd this weekend has been fantastic. It wasn’t my weekend, but things are heading in the right direction.
“I wouldn’t say I’m at my peak at the minute, but I’m starting to get there. I won a title in the week, another final today, and this was good practice for the World Matchplay.
“It’s just the beginning again, and I’m sure I have got many more majors left in me.”
European Tour debutant Sykes was one of the stories of the weekend, reaching the semi-finals after victories over Niko Springer, Martin Schindler, Cameron Menzies and Jermaine Wattimena.
Results
Last 16
Rob Cross 6-5 Kevin Doets
Nathan Aspinall 6-0 Ryan Searle
Tom Sykes 6-4 Cameron Menzies
Jermaine Wattimena 6-5 Danny Noppert
Andrew Gilding 6-4 Michael van Gerwen
Ross Smith 6-4 Chris Dobey
Mike De Decker 6-5 Ryan Joyce
Wessel Nijman 6-1 Stephen Bunting
Quarter-finals
Rob Cross 6-2 Nathan Aspinall
Tom Sykes 6-2 Jermaine Wattimena
Ross Smith 6-4 Andrew Gilding
Wessel Nijman 6-3 Mike De Decker
Semi-finals
Rob Cross 7-2 Tom Sykes
Wessel Nijman 7-6 Ross Smith
Final
Wessel Nijman 8-3 Rob Cross