D'Arcy has recovered from the dead leg he sustained in last weekend's 30-22 victory over Wales, while O'Mahony has been given the all-clear after suffering concussion in the same match.
An attritional championship opener at the Millennium Stadium also saw centre Brian O'Driscoll, flanker Sean O'Brien, full-back Rob Kearney and prop Mike Ross suffer knocks that have cleared up during the week.
Substitute centre Keith Earls takes his place on an unchanged replacements bench after damaging his shoulder against Wales.
"The players have recovered pretty well from the Wales game. We took 48 hours off after the match and have toned down training since," said head coach Declan Kidney.
"Gordon, Peter and Sean all trained fully this morning so we don't envisage there being any changes."
Irish coach Declan Kidney revealed that Chris Henry was close to selection following his impressive cameo at the Millennium Stadium while the Leinster pair Luke Fitzgerald and Fergus McFadden were unlucky not to be named in the 23-man squad.
“We took a look at each position. Obviously there were a lot of hard calls going into last week. Guys came on like Chris Henry and had a great stint,” he said.
“Fergus and Luke have been training really well, it was difficult to leave them off.”
“We’re focused on the task at hand and that’s England. This is probably going to be as tough if not tougher than last week (against Wales). It’s a big challenge,” he said.
“We really didn’t do the jersey proud (last year in Twickenham) and not many people could put their hand up and say we did a good job today. Like any job you always want to do your best and that day we were second best.”
“It was a tough day at the office but you learn from it and we learned a lot from that day.”
Sunday's showdown at Lansdowne Road has been billed as an early title decider after France slumped to a shock defeat by Italy last weekend.
England's last Six Nations victory in Dublin was in 2003 when they won the Grand Slam, an achievement they only failed to repeat in 2011 when they were routed 24-8 in the Irish capital.
The tables were turned 12 months ago when Ireland were crushed 30-9 at Twickenham thanks to an early injury to tighthead Mike Ross that resulted in their scrum being taken apart.
Seven wins in nine championship meetings have seen the Irish dominate the fixture in recent times, but bookmakers are unable to split them with both teams valued at 10/11.
On the pitch there are several intriguing duels that will have ramifications for Lions selection this summer, among them Jonathan Sexton and Owen Farrell battling it out at fly-half.