Newcastle also won the BBL Cup this season
Newcastle Eagles came from behind to win the BBL play-offs with a 68-66 win over the London Lions.
Cortez Edwards scored 22 points and Evan Maxwell added 14 in the Eagles' seventh play-off finals win.
Orlando Parker hit 27 points and Deandre Liggins added 12 for London, who won the BBL Trophy this season.
The win also prevented a Lions double after their women's team won the WBBL play-offs title for the first time ever in the earlier final in Leicester.
The Eagles had finished fourth in the league this season and flirted with elimination in the semi-finals against league champions Leicester.
The Lions were playing without their captain and two-time BBL player of the year Justin Robinson, who was ruled out with a knee injury suffered during their run to the final.
That seemed not to be an issue when they opened up a 24-12 lead at the end of the first quarter, with Parker hitting 15 of those points.
But Newcastle, with veteran guard Rahmon Fletcher running the team and Edwards in peak form, hit 11 of the first 14 points of the second quarter to bring them back into the game.
London established another 12-point lead in the third quarter as former NBA player Liggins drove the team towards a second title of the season, only for six points from Edwards to bring Newcastle back into contention.
Newcastle posted a brief lead at the start of the fourth quarter but the scores were level at 66-66 with 1:34 remaining.
Although Newcastle missed four free throws in the remaining time, London's failure to score in their final four attempts meant that Edwards' two shots from the line with 46 seconds remaining clinched the game for his team and the Most Valuable Player award for himself.
"I think our defence was incredible and we did a great job defending the three-point line," said Eagles coach Ian Macleod.
"We're three out of three in finals in the most difficult year most of us will ever remember," he added, referring to his team's wins in the 2020 Trophy Final and January's Cup final.