In a thrilling exhibition at Kings Park on Saturday, the home side largely dominated the first half until centre Juan de Jongh's late try – the only one of the game – enabled the visitors to take a 16-12 advantage at the break.
That appeared to shift the momentum, and after flyhalf Patrick Lambie, who kicked all the points for the home side, briefly put his team back in front, the outstanding Demetri Catrakilis slotted over two drop goals that sealed a thrilling win.
Province claimed their first title since 2001 when they beat the Sharks in the domestic final in Cape Town.
It was also the third straight final loss for the home side, who were beaten in last year's domestic showpiece and the Super Rugby decider earlier this year.
Province took the lead inside the opening three minutes when Springbok flanker Willem Alberts was penalised for side entry, allowing number 10 Catrakilis to pop over the first points.
Lambie hit back for his side moments later when the visitors were punished for an accidental offside.
The frantic early pace continued and it took a superb last-ditch tackle from Bryan Habana to deny JP Pietersen from scoring after Paul Jordaan cut through and passed inside.
The hosts went ahead after 13 minutes via another Lambie penalty, awarded when a struggling Habana, who subsequently went off injured, slowed the ball down.
Province then got on the front foot for the first time in the game, but Pietersen intercepted and booted forward as the Sharks won another penalty.
Lambie extended the lead to six points midway through the opening period, before adding another straight after a fierce scrum by his forwards.
A Jannie du Plessis shoulder charge offered Province a chance to stay in touch and Joe Pietersen, who replaced Habana, knocked over a tricky kick from near the halfway line.
That sparked some life into the Capetonians and they went ahead through a converted try, scored by De Jongh after he escaped a few half-tackles, side-stepped Lwazi Mvovo and ran in under the posts.
Catrakilis added his second penalty after the hooter had sounded to give Province a four-point advantage at the interval.
That was cut to one point straight after the break, thanks to another powerful scrum by the Sharks forwards and a fifth successful Lambie penalty.
Plumtree's men threw everything forward for the next 10 minutes, but failed to come away with a try in the face of a dogged visiting defence.
They did take the lead when Province failed to roll away and Lambie sent over a penalty, although another Catrakilis effort shifted the advantage once again.
The young Province flyhalf then sealed the win with two drop goals as the visitors were crowned worthy winners. – Sapa