Wainwright, who excelled for Wales during the autumn internationals, is the only change to the side that started the home victory over Edinburgh.
Head Coach Bernard Jackman names a match day squad where all 23 players are Welsh qualified – and 11 players came through the Dragons pathway.
Wales internationals Cory Hill, Ross Moriarty and Elliot Dee all return to the bench for the clash with Leinster.
Scrum half Tavis Knoyle is also recalled among the replacements while hooker Richard Hibbard will once again captain the Dragons from the front row.
Head Coach Jackman said: “It’s a massive game for us and we know we must raise our performance levels if we are to compete.
“There were elements of last weekend’s game with Edinburgh that were very pleasing and we need to ensure we now build on that.
“We’ve integrated our Welsh internationals back into the set-up this week and it’s a boost to have them involved
“When Leinster hit top form they can be devastating, as we saw when they beat Wasps in Europe and last week against Ospreys,” he added.
“When we played them in Round 3 we played 25 minutes with 14 men and it was difficult. Our discipline has to be spot on and the improvement with our defence needs to continue. It will be tested under the most extreme circumstances and we have to be ready.”
Hugo Keenan, Adam Byrne, Jimmy O’Brien, Conor O’Brien, Dave Kearney, Ross Byrne, Jamison Gibson-Park; Ed Byrne, James Tracy, Michael Bent, Ross Molony, Scott Fardy, Josh Murphy, Scott Penny, Caelan Doris
Replacements:Bryan Byrne, Peter Dooley, Andrew Porter, Mick Kearner, Max Deegan, Paddy Patterson, Ciarán Frawley, Tom Daly