Littler had navigated a challenging route to the finale, beating Jeffrey de Graaf, Ross Smith, Ricardo Pietreczko and Chris Dobey before overcoming Gerwyn Price 11-8 in the semi-finals.
Aspinall, ranked 21 in the world, entered the showdown in a confident mood after easing past Jermaine Wattimena 11-2, but was ultimately unable to derail the teenage darting prodigy.
Littler raced into a 5-2 lead, only for the Asp to fight back with a spirited run, highlighted by a 127 checkout that reduced the deficit to 9-8.
The 18-year-old, however, held his nerve to seal the title with an assured 88 finish.
"It wasn’t easy to reach the final, but I’m proud to tick this one off the list... only two more to go," Littler said after his latest triumph.
"I played brilliantly throughout, and I’m glad I got the job done as we look ahead to the big one next month."
Aspinall, bidding for his third televised ranking title, has nonetheless enjoyed a strong week, rising six places to world No. 15.
His run to the final included wins over Karel Sedlacek, Richard Veenstra, Danny Noppert and Josh Rock.
"This has been a fantastic tournament," Aspinall said. "I’m back in the top 16, which was a big target, and the support here in Minehead is always amazing.
"I’ve got to congratulate Luke - he’s incredible and it’s been great to share the stage with him."
Results
Quarter-finals
Gerwyn Price 10-6 Daryl Gurney
Luke Littler 10-5 Chris Dobey
Nathan Aspinall 10-8 Josh Rock
Jermaine Wattimena 10-8 James Wade
Semi-finals
Luke Littler 11-8 Gerwyn Price
Nathan Aspinall 11-2 Jermaine Wattimena
Final
Luke Littler 11-8 Nathan Aspinall
Van Veen holds off Greaves
Earlier in Minehead, Gian van Veen successfully defended his World Youth Championship crown, beating Beau Greaves 6-3.
The 23-year-old, who recently claimed the European Championship, produced two 13-darters and a 118 checkout to secure the victory.
Van Veen becomes only the second player, after Dimitri Van den Bergh, to win successive World Youth titles.
Greaves mounted a brief comeback but was ultimately undone by missed doubles.
