Littler raced to a 4-0 lead in the finale, before Humphries was able to pull one back.
But 'The Nuke' then quickly took the next two sets for the win in just 12 minutes.
Littler 'nilled Stephen Bunting in the quarters, before beating Rob Cross 6-3 in the semi-finals.
Humphries, however, was amply tested by both Chris Dobey (6-3) and Nathan Aspinall (6-5).
'The Asp', it must be said, looked to be in for a special night after beating Michael van Gerwen 6-5 in the quarter-finals - but the world number one got the better of the Stopfordian.
Welsh star Gerwyn Price had a night to forget after being easily dispatched by Cross in the first round.
By beating Humphries, Littler has extended his lead atop the Premier League to eight points (on 26) - with 'Cool Hand' following closest (18).
Results
Quarter-finals
Luke Littler 6-0 Stephen Bunting
Gerwyn Price 2-6 Rob Cross
Luke Humphries 6-3 Chris Dobey
Michael van Gerwen 5-6 Nathan Aspinall
Semi-finals
Luke Littler 6-3 Rob Cross
Luke Humphries 6-5 Nathan Aspinall
Final
Luke Littler 6-1 Luke Humphries