Daniel Gilbert hit five three-pointers in his 27 points to lead the Guildford Heat to a 100-88 win over Milton Keynes in the BBL play-offs final.
Mike Martin added 25 points and Tony Dorsey 19 for the Heat, whose 21-9 run in the fourth quarter secured victory.
The Lions were led by 22 points from their captain, Dru Spinks, at Birmingham's National Indoor Arena.
The title is Guildford's second trophy of the season and fourth in the last two years.
Guildford began their push for victory in the third quarter, when Gilbert hit two three-pointers in a 10-2 run.
He hit another three-pointer in a 15-2 run in the fourth quarter that produced an 83-68 lead for the Heat, before the Lions threatened a dramatic late comeback.
Spinks hit 10 points in a row, cutting the lead to seven points with 1:19 remaining.
But Dorsey scored the next four points for Guildford after Lions coach Vince Macauley was awarded a technical foul for dissent and Guildford were home and dry.
"We just buckled down and played defence from the beginning of the play-offs - even against Everton in the quarter-final," said Gilbert.
"That's what's been working for us all season.
"Before we even came into this game we knew we were going to win it.
"We came here knowing we were going to win the play-offs - that's the sort of focus and determination we came here with.
"Mike (Martin) could easily have been the MVP - he deserved it. And Tony Dorsey's been solid all season for us."
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