The Warriors showed the strength of their regional squad with a hard-fought Celtic League win at Donnybrook.
Leinster (16) 16
Try: F Contepomi
Pens: Contepomi (3)
Warriors (17) 37
Tries: R Mustoe, S Martens, S James, J Bryant
Cons: N Jenkins (4)
Pens: Jenkins (3)
The Welsh held a narrow 17-16 lead at the break, with Felipe Contepomi having scored all the home side's points.
But at the beginning of the second half Jon Bryant broke the midfield and fed Shaun James for the decisive score.
Bryant's last-minute try secured the bonus point, Neil Jenkins converting to extend his run of successful kicks at goal to 44.
Jenkins' 100% record stretches back to 31 October.
It was a confident start from the Warriors, Chris Horsman leading a strong sixth-minute forward drive deep into the Leinster
The ball was fed back to Jenkins who passed for Richard Mustoe to score wide on the left.
The visitors were on the charge again when an over-complicated midfield move saw Contepomi intercept a Bryant pass
and run in from 80m.
Straight from the restart, Sililo Martens restored the Warriors' lead, spotting a shuffling defence at a ruck and jinking
back inside for a neat try.
But Welsh indiscipline cost them, Rob Dickson penalising heavily and Contepomi adding the punishment with three kicks to
edge the Lions ahead 16-14.
Just before the break, Dickson awarded the Warriors their first penalty of the night and Jenkins' boot gave the visitors a
narrow 17-16 half-time lead.
They carried the momentum into the second period, Bryant straightening the line superbly to split the Leinster defence
before feeding Shaun James for a score under the posts.
It proved the crucial moment as the Warriors' extra physicality kept the Lions penned deep in their own half.
Jenkins landed two more penalties to make the lead secure as the visitors prepared for a last-gasp attempt to secure the
fourth, bonus-point try.
That crucial score came in the fourth minute of injury time, turnover ball from forward pressure being fed to Bryant who blasted over from short range.
"It was a difficult match and we're delighted, especially to come away with a crucial bonus point," said man-of-the-match Bryant.
"They're a big, physical side, but we had a game plan to come here and move them around."
Leinster: James Norton; John McWeeney, Gary Brown, Christian Warner, Brendan Burke; Felipe Contepomi, Brian O'Riordan; Sean Brophy, Gavin Hickie, Peter Coyle, Aidan Kearney, Ben Gissing, Niall Breslin, Shane Jennings (capt), Des Dillon.
Replacements: Enda Bohan, David Blaney, Simon Crawford, Ciaran Potts, Brian O'Meara, Matt Leek, James Downey.
Warriors: Gareth Wyatt; Dafydd James, Shaun James, Jon Bryant (capt), Richard Mustoe; Neil Jenkins, Sililo Martens; Chris Loader, Matthew Rees, Chris Horsman, Nick Kelly, Deiniol Jones, Ryan Jones, Cory Harris, Richard Bryan.
Replacements: Christian Balshen, Martin Jones, Richard Parks, Maama Molitika, Paul John, Emyr Lewis, David Bishop.
Referee: Rob Dickson (Scotland).