The world number one tasted glory on the PDC's World Series of Darts circuit for just the second time with the triumph, sinking to his knees after hitting the winning double in front of 4,000 fans in The Theater at Madison Square Garden.
The success for Humphries follows victories in the World Masters and Premier League this year, as he continued his big-stage form with another impressive title.
He defied a typically determined fightback from Aspinall to prevail in the decider, with the 2019 US Darts Masters champion hitting back from 3-0 down to level at five-all with a clutch 90 finish on the bullseye.
Humphries, though, showed his class with a 142 checkout to respond in style, and he held his nerve before landing double eight to seal a memorable triumph. Humphries followed up Friday's first round defeat of Stowe Buntz by ending American hopes in New York with a 6-2 quarter-final win over Danny Lauby.
He then reeled off five straight legs to pull clear from two-all to win his semi-final with Gerwyn Price 7-2. Aspinall had overcome top-ranked Canadian Matt Campbell in Friday's first round, and continued his superb form to take victory in a quarter-final of the highest quality against Luke Littler.
The World Champion averaged almost 109 in a 6-4 defeat, as Aspinall averaged 106 to book his spot in the semis, where he defied a 170 checkout from Damon Heta to claim a 7-3 win.
Earlier, Price was a 6-3 winner over two-time US Darts Masters winner Michael van Gerwen in their quarter-final, while Heta whitewashed American qualifier Jason Brandon - who had knocked out Rob Cross 24 hours earlier.
The PDC's World Series of Darts continues next weekend with the Superbet Poland Darts Masters in Gliwice, where a 16-player field will compete on July 4-5.
2025 bet365 US Darts Masters
Quarter-Finals
Damon Heta 6-0 Jason Brandon
Nathan Aspinall 6-4 Luke Littler
Luke Humphries 6-2 Danny Lauby
Gerwyn Price 6-3 Michael van Gerwen
Semi-Finals
Nathan Aspinall 7-3 Damon Heta
Luke Humphries 7-2 Gerwyn Price
Final
Luke Humphries 8-6 Nathan Aspinall
Campbell had claimed the top domestic honour 12 months ago in The Theater at Madison Square Garden, and scooped the $10,000 top prize in style.
2025 bet365 North American Championship
Saturday June 28
Afternoon Session
Quarter-Finals
Matt Campbell 6-1 Jason Brandon
Stowe Buntz 6-0 Jules van Dongen
Danny Lauby 6-1 Leonard Gates
Jim Long 6-4 Adam Sevada
Semi-Finals
Matt Campbell 6-2 Stowe Buntz
Jim Long 6-1 Danny Lauby
Final
Matt Campbell 6-3 Jim Long
