Tom Kimber hit a stunning 82 not out as Guernsey completed their World Cricket League Division Six campaign with a fifth straight win against Malaysia.
Chasing 208-9 against the hosts, Guernsey were in trouble on 65-7 when Kimber came in to join David Hooper.
But the young keeper hit nine fours and a six in his 92-ball knock, supported by Hooper (45), as Guernsey reached 211-8 to win with three balls left.
Having sealed promotion, Guernsey's two-wicket win meant they finished top.
GH Smit took three wickets as Guernsey ended with a perfect record of five victories out of five to win their first ICC tournament.
Jeremy Frith was named player of the tournament for his efforts with both bat and ball.
"It feels simply brilliant to win today," said skipper Stuart Le Prevost, "especially to have been seven down and then see young Tom Kimber come out and guide us to victory with a fantastic knock."