Willey was the unfortunate bowler to accommodate Jofra Archer in England's World Cup squad, but the Yorkshire left-armer claimed a maiden five-for at global level on his comeback in front of empty seats at the Ageas Bowl.
David Willey opened the bowling for England in his first worldwide appearance since making way in the World Cup squad for Jofra Archer and the left-arm seamer made a breakthrough within four balls.
Willey took 4-12 as Ireland slumped to 28-5 after losing the toss.
This series, with all three games played at the bio-secure Ageas Bowl without spectators, marks the start of the International Cricket Council's World Cup Super League - the qualification pathway to the next 50-over World Cup where England will look to defend their title in India in 2023.
Willey struck with just the fourth ball of the match when Paul Stirling chipped him to Morgan at midwicket.
The South Africa-born batsman shared half-century stands with the experienced Kevin O'Brien (22) and Andy McBrine (40) as Ireland recovered from their awful start.
Ireland were in danger of being dismissed for under 100 but all-rounder Curtis Campher held firm with an unbeaten 59 on debut.
It got even better for Willey when Gareth Delany sliced to backward point to end a counter-attacking 22 while Lorcan Tucker departed next ball, lbw after a review showed the delivery would have crashed into leg stump.
Tector's maiden ODI innings lasted just nine deliveries but fellow newbie Campher fared much better, facing 118 deliveries in his unbeaten half-century and passing fifty from his 103rd ball - Campher becoming the third Ireland player, after Morgan and Andre Botha, to hit a fifty on debut. However, before coming into this series, the pacer had missed England's last 22 white-ball games.
McBrine initially matched Campher's willingness to dig in before taking the attack to Tom Curran, who had his revenge when the lower-order batsman holed out after making 40 from 48 balls before Willey fittingly ended Ireland's innings by snaring Craig Young, who toe-ended to mid-off.
Willey - so close to appearing in the previous World Cup - struck in his first and second overs after England elected to bowl, setting him on the way to beat his previous best figures of 4-34, which he had managed against Sri Lanka in Cardiff in 2016.
Banton top-edged Campher behind on the pull as Ireland made another key breakthrough, having earlier seen Bairstow and Roy fall lbw to McBrine and Young respectively and Vince then clip Young behind.
It is his side's first home ODI since their World Cup win in July 2019.
England's red and white-ball fixtures are overlapping in a season cut short by the COVID-19 outbreak and they are maintaining two separate squads, meaning several World Cup winners including Joe Root, Ben Stokes and Archer won't feature against Ireland.