Dobey looked down and out when the brilliant De Sousa, who had come from 3-0 and 4-1 down, fired in a 122 checkout to move 7-6 up and one leg away from his third triumph of a sensational season but he then squandered four match darts to seal the deal.
The 31-year-old capitalised to force a decider but it was then his turn to seemingly blow his big chance when failing to take out 56 after De Sousa left himself on 30 after agonisingly missing a dart at the bull for a 170.
The Premier League runner-up then missed all three attempts to pin double 15 and Dobey, who averaged 97 compared to De Sousa's 104, finally held his nerve to pin tops and complete an emotional victory.
"I've played in local competitions and last-leg deciders have been my game, and I've proven it today. I was down and out against Willie Borland, same against Stephen Bunting.
"I don't think I've ever lost against Jose - I've got a great record.
"I've never been so nervous in my life going for those doubles [at the end of the final]. They weren't far away but he missed doubles, he probably should have won but I've done it now.
"I've had the experience of being in finals before but I haven't got over that winning line. I've said for a long time now that once I get that first one then hopefully I can get some more under my belt."
Tuesday's event saw Dobey reach his first final for over two years and was also the first time in 2021 where he has won past the last 16, giving him hope of claiming a return to the World Matchplay later this month.
"I was a mile out before this week," he admitted. "I've been playing well for quite a few months and had no luck whatsoever.
"It will be amazing to play in front of fans again - I think that's what everybody's missing. Hopefully I can keep performing like I did today, and who knows."
Tuesday's event saw Dobey reach his first final for over two years and was also the first time in 2021 where he has won past the last 16, giving him hope of claiming a return to Blackpool later this month.
"I was a mile out before this week," he admitted. "I've been playing well for quite a few months and had no luck whatsoever.
"It will be amazing to play in front of fans again - I think that's what everybody's missing. Hopefully I can keep performing like I did today, and who knows."
De Sousa had come from 6-4 down in the semi-finals against Ryan Searle to claim the last three legs, surviving three missed match darts from the Englishman and taking out 152 and 107 to book his spot in the decider.
He also defeated Darius Labanauskas in a deciding leg, but dropped just a total of six legs in other wins over Mervyn King, Steve Lennon, Jelle Klaasen and Adam Gawlas.
Searle and Kuivenhoven were narrow semi-final losers, while King and Bunting were joined in the quarter-finals by Scott Mitchell and Croatia's Boris Krcmar - who picked up a memorable win over World Champion Gerwyn Price as he reached the last eight for the second time in 2021.
Tuesday's event also featured the rare achievement of nine-dart finishes from both players in a match, as Danny Noppert and then Martin Atkins landed perfect legs in a second round tie which Dutchman Noppert won 6-3.
The week's action at the Coventry Building Society Arena continues on Wednesday with Players Championship 19, with play commencing at 1200 BST.
Last 16 onwards. For all the results and detailed stats from the Super Series, head to ()
Last 16
Quarter-Finals
Semi-Finals
Final