St Paul's captain Stuart Andre with the James Marquis Trophy
St Paul's finally won the Dandara Premiership title at the third time of asking with a 1-0 win at Grouville.
The only goal came from JP Martyn's 25-yard lob after just nine minutes.
Grouville's chances were not helped by the dismissal of Craig Northedge for a second bookable offence early in the second half.
St Paul's have now won three of the six trophies available to them, including the Upton, in which they will hope to be crowned Channel Island champions.
St Paul's had needed just one win from their final three matches, but both Jersey Scottish and then St Ouen held them to draws in recent weeks.
Grouville were the only side that could have forced a play-off by winning their last four games.
But Grouville's consolation after this defeat will be that they only need a single point from three matches to secure runners-up spot.
St Paul's still have their eyes on three more possible trophies, the Wheway and Jeremie Cups, and the Upton.
Captain Stuart Andre hopes his side can now secure an unprecedented six-trophy haul.
"I think we deserved it," he told BBC Radio Jersey. "It's been hard over the last couple of weeks getting over the finishing line.
"But today we fully deserved it and could have won by a lot more.
I think this St Paul's team will be spoken about for many years to come.
St Paul's manager Craig Culkin
"We'll take each game as it comes but we're a great bunch of lads. We'll work for it and have a go."
Manager Craig Culkin put some perspective on what his side had achieved.
"Unbelievable," he said. "Sixteen league games, 13 wins and three draws. Three consecutive league titles. This St Paul's team will be spoken about for many years to come."
St Paul's president Charlie Browne added: "We've waited three games for this. It's a reward for all the volunteers within the club from our Under-8s to our learning disability team."
St Paul's now play Guernsey League champions Belgrave Wanderers in the Upton final on 17 April, when the winners will be crowned Channel Island champions.
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