Ireland's 118 was arguably never going to be enough for them as England captain Nat Sciver-Brunt top-scored with 48 to help them chase it down with 15 balls to spare.
However, Ireland had their moments. Early wickets are needed when defending a low total and the Ireland bowlers delivered. Almae Maguire struck twice in the 5th over to dismiss England's opening pair of Amy Jones and Danni Wyatt-Hodge, then Orla Prendergast yorked Alice Capsey to leave them floundering at 35/3.
But veterans Sciver-Brunt and Heather Knight steadied the ship and took the game away from Ireland with a 64-run stand that put them on the brink. There were a few consolation wickets at the death, but England were home comfortably.
Earlier, Ireland were in trouble quickly. England seamer Linsey Smith cleaned up Amy Hunter in the second over, Lauren Bell dismissed captain Gaby Lewis for a duck, and Charlie Dean picked up Alana Dalzell to leave Ireland 25/3.
Predergast and Rebecca Stokell rebuilt somewhat, but the effervescent Sophie Ecclestone ripped through the Irish middle order. The spinner picked up 3/22 as Ireland slumped to 118/9.