Nijman - who had claimed Players Championship 21 on Tuesday - resumed his resounding form at the Incheba Expo to become the first-ever winner of the Slovak Darts Open.
The Dutchman follows the footsteps of Phil Taylor, Michael van Gerwen and Peter Wright in becoming just the fourth player to have claimed eight or more ProTour titles in one season, while becoming the first player in 2026 to claim multiple European Tour titles.
The 25-year-old blew away Cross in the final with an exceptional display, taking out two ton-plus finishes and four legs on the spin to lead 5-2.
Although Cross produced a valiant display himself and averaged north of 102, Nijman relentlessly ploughed on, taking out a 12-dart break before wrapping up victory with a 74 outshot - finishing the contest with a 103.80 average.
“I cannot put this into words. It’s so amazing,” confessed Nijman, who climbed to world number 14 after becoming the inaugural Slovak Darts Open champion.
“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 kicked off his title bid with comprehensive victories over Benjamin Pratnemer and Stephen Bunting, including a 6-1 win over the latter after missing just a sole dart at double across the contest.
The Dutchman then produced a wondrous display to shrug off Mike De Decker in the quarter-finals, conjuring a 170 finish and producing a 104.50 average.
In the last four, the former Development Tour winner almost let a 5-2 lead slip against Ross Smith, but took out 341 in six darts in the last-leg decider to clinch his spot in the showpiece.
2026 Slovak Darts Open
Sunday June 21
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