The former Bath centre slotted the second of his close-range deep in injury-time as the Irish province bounced back from a shock opening Magners League defeat to the Scarlets.
Martyn Thomas had breathed fire for the visitors with a well-worked second try and James Arlidge then put the Gwent region within touching distance of gaining a solitary point with a 74th minute penalty before Berne’s strike with the final kick of the match.
British Lions centre Gordon D’Arcy set up Isa Nacewa for the decisive score in the 52nd minute as the Heineken Cup champions celebrated their homecoming in emphatic style.
The kings of Europe made their first appearance at the Royal Dublin Showground since lifting northern hemisphere’s biggest prize back in May. And Leinster were handed a huge ovation as they took to the field from the vociferous crowd.
But Paul Turner’s men were intent on spoiling the party and the game to the hosts from the kick-off.
Leinster eventually settled down and were rewarded with a 13th minute lead thanks to Jonathan Sexton’s close-range penalty.Dragons fly-half James Arlidge tied the scores four minutes later before the Gwent region pressed the self-destruct button twice in the opening half.
Gavin Thomas was sin-binned by Scottish referee Graham Knox in the 19th minute for an infringement before centre Ashley Smith was later yellow-carded for diving off his feet.
The ice-cool Sexton capitalised on both occasions to nudge Leinster 9-3 ahead but despite playing 20 minutes with a numerical disadvantage, the visitors could finish the half in good heart.
Leinster briefly threatened the Dragons’ try-line with Shaun Berne going close twice but the Dragons’ much-improved defence, inspired by Colin Charvis, held firm.
Arlidge had missed an earlier drop-goal attempt but struck gold on the stroke of half-time. Dragons skipper Luke Charteris failed to re-appear for the second half while Leinster introduced Lions stars Nathan Hines and D’Arcy. The tactical switch worked a treat for the hosts inside 60 seconds for the opening try. Sexton began a flowing move and D’Arcy’s first touch sent Nacewa over in the right corner.
Berne’s first drop-goal and Sexton added three-pointers either side of Thomas’ try from Richard Fussell’s pass in the right corner. Arlidge hammered home a penalty to give the Dragons a glimmer of hope before Berne’s last-gasp drop-goal from close range.
