Ryan Giggs’ men kicked off their Nations League campaign with an emphatic victory, which was sealed by goals from Tom Lawrence, Gareth Bale, Aaron Ramsey and Connor Roberts.
Shaun Williams got one back for Ireland, whose line-up included Magpies defender Ciaran Clark, but it was Wales’ night at the Cardiff City Stadium.
And Dummett, who picked up two caps in friendlies against the Netherlands in 2014 and 2015, came on in place of Ben Davies with just under ten minutes remaining to make his first competitive appearance for the Dragons.
Clark, meanwhile, played the full 90 minutes for Martin O’Neill’s side, picking up a yellow card in the process.
United goalkeeper Martin Dúbravka was an unused substitute in Slovakia’s 3-0 friendly win over Denmark on Wednesday night, with Adam Nemec, Albert Rusnak and an own goal from Adam Fogt making sure of a comfortable victory for Jan Kozak’s team.
Another stopper, Freddie Woodman, wasn’t involved for England Under-21s as they drew 0-0 with Holland at Carrow Road.
Salomón Rondón, Fabian Schär, Christian Atsu and DeAndre Yedlin are all likely to be in action for their respective countries in the coming days.