An early Sean Cronin try set Leinster on their way but a dogged and resilient performance from Bernard Jackman’s men saw the full-loaded hosts frustrated for long periods.
But during a harsh yellow card to Ross Moriarty, the home side struck twice either side of half-time, courtesy of Josh van der Flier and Jamison Gibson-Park, to take control.
Jordan Larmour wrapped up a home try bonus point before Dragons full back lit up the stadium with a stunning solo effort from inside his own half.
However, further tries from Gibson-Park, Tadhg Furlong and Scott Fardy sent the hosts clear while Dragons were left to count the cost of a dislocated elbow to wing Hallam Amos late on.
Head Coach Jackman called-up flanker Nic Cudd, prop Lloyd Fairbrother and centre Adam Warren for the clash in Ireland.
Leinster named a stellar starting line-up that was packed full of international experience and captained by British & Irish Lions ace Johnny Sexton.
The home side, back at the RDS for the first time since completing the league and cup double, looked ominously sharp in the opening minutes and had a Garry Ringrose try ruled out early on.
But they only had to wait until the 10thminute to strike when a powerful break from Ireland international Robbie Henshaw split the midfield and Cronin picked up at the breakdown and darted over.
Wave after wave of blue pressure was met by stubborn Dragons defence with the forwards putting in a huge shift to deny the Irish side space.
Dragons almost struck from nowhere when Josh Lewis flew out of the line and almost intercepted a pass from scrum half Gibson-Park.
There was a huge work-rate from Dragons, with the back row trio of Moriarty, Aaron Wainwright and Cudd impressing.
A penalty from Sexton extended the lead just after the half-hour mark, before Dragons enjoyed their best spell of pressure in the half.
Lovely hands from Amos popped a pass out to Jordan Williams before the full back repeated the feat to find Cudd on his shoulder.
However, after working their way up the line, a penalty for not releasing saw momentum stopped.
Leinster made Dragons pay in stoppage time when, moments after Moriarty was carded for a late hit on Sexton, the ball found van der Flier who crashed home.
Fly half Lewis ate into the lead at the start of the second half with a penalty – via the left-hand upright but within minutes the home side were over for a third score through Gibson-Park.
The scrum half then turned provider as he stepped inside a tackle and kicked ahead for Larmour to win the foot-race to the corner.
Gibson-Park darted over for his second from close range before the try of the game from an inspired Williams who picked the ball up inside his own half, stepped inside and then glided past tackles to score a superb solo effort.
Late tries from Furlong and Fardy took Leinster past the half century while Dragons played the final quarter with a man less after Amos was taken off with his elbow injury.
10m Cronin t Sexton c 7-0
31m Sexton p 10-0
40m Van der Flier t Sexton c 17-0
43: Lewis p 17-3
45m Gibson-Park t Sexton c 24-3
49m Larmour t Sexton c 31-3
58m Gibson-Park t Sexton c 38-3
61m J Williams t Robson c 38-10
64m Furlong t Sexton c 45-10
77m Fardy t Reid c 52-10
Dragons: 15 Jordan Williams, 14 Dafydd Howells, 13 Adam Warren, 12 Jack Dixon (Sage 60), 11 Hallam Amos, 10 Josh Lewis (Robson 60), 9 Rhodri Williams (Knoyle 51); 1 Brok Harris (Bevington 41), 2 Elliot Dee (Hibbard 51), 3 Lloyd Fairbrother (Harris 51 (Brown 73)), 4 Matthew Screech (Nansen 41), 5 Cory Hill, 6 Aaron Wainwright (Griffiths 48), 7 Nic Cudd, 8 Ross Moriarty
Replacements: 16 Richard Hibbard, 17 Ryan Bevington, 18 Leon Brown, 19 Brandon Nansen, 20 Ollie Griffiths, 21 Tavis Knoyle, 22 Arwel Robson, 23 Jarryd Sage
Referee: Quinton Immelman (SARU)