The City forward was surprisingly omitted from the Three Lions squad for the European Championship in the summer but went straight back into the starting line-up for the impressive win in Dublin.
The game was the first in charge for former Manchester City Under-18s manager Lee Carsley who has taken over as interim manager from Gareth Southgate.
As well as recalling Grealish, Carsley also named Rico Lewis and John Stones in his first squad with the latter a late introduction from the bench at the Aviva Stadium.
Phil Foden was initially in the squad but withdrew due to illness that ruled him out of our last two Premier League matches against Ipswich and West Ham.
And it took just 10 minutes for the first goal of Carsley’s tenure - coming from Declan Rice who had played in three friendlies for Ireland earlier in his career before switching to England.
Newcastle winger Anthony Gordon raced onto a througball but was denied by Liverpool’s Caoimhin Kelleher before the ball broke for Rice who smashed it into the top corner.
It was a more attacking and creative England with Harry Kane going close to a second from close range before Grealish doubled England’s lead.
Neat passing opened up the Ireland defence before the ball was worked to Grealish on the edge of the box and he elegantly stroked a right foot shot into the bottom corner.
The home team tried to find a way back into the game in the second half with Sammie Szmodics dragging a shot off target but England remained largely in control.
Grealish was substituted with 12 remaining as Carsley handed debuts to Morgan Gibbs-White and Angel Gomes while Stones came on the 85th minute.
Fellows substitute Jarrod Bowen twice went close to a third but was denied by smart saves from Kelleher who then made his best stop in injury time from Bukayo Saka.
England are back in action on Tuesday 10 September when they face Finland at Wembley before the players return to their clubs ahead of next week’s Premier League games.
Elsewhere in the Nations League, Nathan Ake started for the Netherlands in their victory over Bosnia and Herzegovina.
The City defender played 66 minutes of the 5-2 victory in Eindhoven as goals from Joshua Zirkzee, Tijana Reijnders, Cody Gakpo, Wout Weghorst and Xavi Simons got the goals.
