The European champions ran in four tries, two each for Sean Cronin and Dave Kearney, at Rodney Parade to record their eighth victory on the spin.
Leinster were bolstered by the presence of full-back Luke Fitzgerald, scrum-half Eoin Reddan, hooker Cronin and lock Devin Toner, who five days earlier had been on RBS 6 Nations bench duty for Ireland against Scotland.
And they proved far too strong for the Dragons, who had won four of their last five matches in all competitions but never looked like derailing Leinster's play-off push.
The hosts had suffered a 60-3 humiliation at the hands of second-placed Glasgow in their last home outing and although this defeat did not plumb those depths, they were outclassed by the Irish province.
It took just 50 seconds for the visitors to cross the whitewash with Cronin barging over down the left for a try which Ian Madigan converted.
Dragons fly-half Steffan Jones kicked a penalty but Cronin scored a replica of his first try to make it 12-3 before seven minutes were on the clock.
Leinster had their bonus point well within sight when Kearney was put over down the right on 18 minutes following a powerful Rhys Ruddock run, Madigan again converting.
But, despite centre Jack Dixon being sin-binned for a breakdown infringement, the hosts finally managed to stem the tide.
And it was 19-9 as the teams headed for the changing rooms courtesy of Jones adding a penalty and a smart drop goal for the Dragons.
Suddenly the hosts had the momentum and when number eight Ieuan Jones crossed just a minute after the restart the home crowd were scenting a remarkable comeback.
But Leinster took a few deep breaths and composed themselves. They laid siege to the Dragons' line and the pressure eventually told with the bonus point score, Kearney the beneficiary of an overlap down the right.
Madigan converted majestically and at 26-14 the wind was taken out of the hosts' sails.
Leinster, who headed into the game as the league's top points scorers, went on the search for more tries.
However, it was the Dragons who had the final say with Steffan Jones reaching out over the line with the last play to ensure the Pro12 strugglers did at least get a bonus point for their efforts.
Scarlets climbed back into the RaboDirect Pro12 play-off places but that was after securing an unconvincing 14-13 victory over struggling Edinburgh at Parc y Scarlets.
Scarlets surrendered an early 8-0 lead before replacement fly-half Owen Williams kicked a penalty 13 minutes from time which was enough to condemn Edinburgh to an 11 straight defeat in all competitions.
Ulster were held 29-29 by Treviso in an extraordinary match at Ravenhill, with Treviso's Budd scoring his third try of the match in the final second as the Italian side completed an outrageous comeback to snatch a draw which means Mark Anscombe's men have won just one of their last four games.
A hat-trick of tries from flanker Dean Budd, a single score from Robert Barbieri and a penalty and three conversions from Alberto Di Bernardo got Treviso the draw, which also saw them register a try bonus only five days after putting Munster to the sword in Italy.
Though they avoided defeat, thanks to tries from Andrew Trimble and Stuart Olding and 19 valuable points from Paddy Jackson, Ulster's slump in form has done considerable damage in their push for a home semi-final.
After leading 20-10 early in the second half, the home side let their lead slip - and their cause was hardly helped by having Iain Henderson and Lewis Stevenson sent to the sin-bin in the first and second halves respectively.
The Italian side sealed the draw in the last move of the game, which could have been a second successive Ravenhill win for them had Di Bernardo landed the difficult conversion from the touchline
Glasgow Warriors ran out easy 29-13 winners over Cardiff Blues thanks to a blitz of three tries in eight minutes in the second half, while Connacht avoided a home defeat against Zebre thanks only to Dan Parks, who landed a 75th minute drop goal and a penalty with the clock in the red to secure a 23-19 win.
- Sports & Recreation
- Sean Cronin
- Steffan Jones