Three second-half goals from three debutants ensured Ireland will go into next month;s crucial qualifiers on a winning note.
Mick McCarthy made 10 changes as he followed through on his promise to use the Republic of Ireland’s friendly against Bulgaria to test the depth of his squad.
Only Conor Hourihane survived from the side which started Thursday night’s Euro 2020 qualifier against Switzerland, and he moved from midfield to left-back in a team captained by Sheffield United defender John Egan.
There were senior debuts for Bournemouth keeper Mark Travers and Charlton midfielder Josh Cullen, while there were chances too for Alan Judge, Alan Browne and Scott Hogan.
Bulgaria boss Krasimir Balakov made nine changes to the team beaten 4-0 by England on Saturday evening, handing debuts to 37-year-old keeper Hristo Ivanov and full-back Georgi Pashov.
The visitors almost took advantage of Ireland’s much-changed defence twice inside the opening 12 minutes with defenders Georgi Pashov and Kristian Dimitrov meeting Nikolay Dimitrov corners, with Travers making a regulation save from the first.
While the Republic were enjoying the lion’s share of the possession, chances were few and far between with Alan Judge heading over and seeing a deflected shot saved by Ivanov.
However, Cullen had to race back to block Daniel Mladenov’s 33rd-minute strike after he had raced clear with the Bulgaria looking dangerous on the break.
Ronan Curtis drilled wide from distance at the other end with four minutes of the first half remaining and then saw his 45th-minute cross only just evade Hogan at full-stretch, and the game remained deadlocked at the break.
Ireland started the second half well, but Egan had to make an important 53rd-minute intervention when he managed to block Mladenov’s shot in the turn after he had controlled Ivan Goranov’s pull-back.
But it was the home side who took the lead three minutes later when Ivanov spilled Curtis’ dipping shot and Hogan turned the ball across goal for Browne to roll it into an empty net.
McCarthy responded minutes later by sending on Jack Byrne and James Collins for Judge and Hogan to hand both first senior caps.
Ireland’s lead was soon extinguished when, after Cyrus Christie had gifted possession to Goranov, he found striker Bozhidar Kraev, who was tripped by Egan and substitute Ivelin Popov converted the resulting 66th-minute penalty.
Defender Kevin Long came to the rescue with seven minutes remaining when he powered home a header from Byrne’s corner to restore the Republic’s lead.
There was more to come when Luton striker James Collins marked his debut with a third four minutes from time when he met fellow substitute Enda Stevens’ volleyed cross to make it 3-1.