The game had several twists but it was three brilliant catches, including a match clincher close to the boundary by Tom Chippendale, which got Hanging Heaton over the line.
The game got off to a pulsating start as Ben Kohler-Cadmore smashed 28 runs off the opening over by Sohail Raz.
Overseas fast bowler Waqas Ahmed bowled Heaton captain Gary Fellows from the first ball of the second over and after he threw down five wides, he then had dangerous number three batsman Callum Geldart bowled the next ball.
When Ahmed had Joe Fraser caught by captain Grant Soames Heaton had slipped to 43-3.
Kohler-Cadmore continued his bruising assault on the Methley attack with a display of powerful hitting.
He blazed seven fours and three sixes — including one through an open clubhouse door, which sent spectators sat inside scattering — on his way to 50 from just 18 deliveries.
Nick Connolly was run out for six and Kohler-Cadmore was caught on the boundary edge by Adam Patel as Raz finally got revenge for his first-over torment.
Heaton were 69-5 after five frenetic overs before Ishmail Dawood and James Keen added 31 runs for the sixth wicket.
Dawood was caught by Ashton Blakey off the bowling of Marcus Walmsley for 14 before Keen was caught behind off a snorting delivery from Adal Islam for 11.
Late order batsmen Aqsad Ali (19), Josh Holling (12no) and Tom Chippendale (11) all made useful runs as Heaton were all out for 166 off the final ball of their 20 overs, with Methley conceding 33 extras including 27 wides.
Ahmed finished with 4-36 while Walmsley’s tidy four over spell saw him end with 2-26.
Chippendale struck early in the Methley innings to remove Adal Islam to a sharp slip catch by Fraser.
Adam Patel took the game to the Heaton bowlers with a series of lovely strokes and Methley had reached 50-1 when Geldart was introduced to the attack and had Dan Shuffe caught by Chippendale off his first ball.
Patel struck 10 off Gledart’s next two deliveries but was then bowled for 48 from 24 balls and the spinner claimed a third wicket in his first over, when the dangerous Walmsley was out to a stunning one handed slip catch by Fraser first ball.
Jordan Laban (13), Blakey (12) and Grant Soames (3) were out in quick succession, the latter becoming Geldart’s fourth victim as he finished with figures of 4-45 and Methley slipped to 95-7.
There were further twists as Jake Smart (29) and Raz (16) made useful runs before Ahmed (25) produced some big hits to get Methley back into the game.
Ahmed hit a couple of boundaries in the final over and the target was down to six runs from the final three balls off Josh Holling.
Ahmed attempted another big hit but Chippendale held his nerve to take a magnificent catch under pressure close to the boundary as Methley were all out for 161.
Hanging Heaton will represent the Bradford League in the ECB National T20 competition when they will have home advantage on July 29.
Heaton face Woodhouse Grange in the first semi-final (start 10.30am) before Barnard Castle take on National T20 Cup holders South Northumberland (1.30pm) with the final to follow at 4.30pm.