Trump made 101 breaks either side of a 92 from Allen to go 2-1 up and went 3-2 ahead with an 88 before the Northern Irishman won back-to-back frames to lead 4-3.
Allen then failed to take a great chance to make it 5-3 as Trump levelled, and the world number two went on to move 5-4 in front via a 135, the highest break of the tournament so far.
After Allen subsequently claimed frame 10 to force a decider, Trump wrapped up victory with a break of 62.
The 32-year-old Englishman – who won the competition in 2019, a year after Allen – said in a post-match interview: “Wow. I’ve been waiting for this for a long time. I’ve lost a few close ones this season and to battle back there…
“It’s just you lose the belief when you lose these close games, but to finish how I did, I’m so proud of myself.”
Trump had given a small fist pump after drawing level at 4-4, and when asked about that, he said: “Normally I’m quite reserved, but I couldn’t help it, with this crowd in here. They pick you up, and I love the sort of rowdiness of this London crowd, it’s amazing.”
He added: “I’m just getting warmed up now. I’m so happy to still be in it.”
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