The 60-year-old, who first managed his country between 1996 and 2002, took over from Martin O'Neill in November, but any thoughts that he would usher in a new era with a swashbuckling win were soon dispelled.
Gibraltar, ranked No.194 in the world, more than held its own in the first half but was ultimately undone four minutes after the restart when Jeff Hendrick stroked home for his second international goal.
The visitors rarely looked like adding to that strike as their Group D campaign got off to a winning start, albeit an extremely underwhelming one.
Ireland was frustrated in the opening stages and had to wait until just before the half-hour mark for its first sight of goal. A superb reaction save from Kyle Goldwin, however, prevented Roy Chipolina's wayward header from finding the back of his own net.
Chipolina was involved again shortly before the interval, blocking David McGoldrick's goal-bound flick, while Conor Hourihane's free-kick from the left fizzed past Goldwin's post in the first half's closing stages.
Skipper Chipolina was denied a famous goal moments after the restart when Darren Randolph instinctively pawed away his close-range header from a corner.
That sparked Ireland into life and it forged ahead in the 49th minute. McGoldrick sped away from Jack Sergeant down the left and picked out Hendrick, who coolly slotted into Goldwin's bottom-left corner from 15 yards.
Shane Duffy headed wide from an in-swinging free-kick in the closing stages as Ireland ultimately edged to the most slender of wins thanks to Hendrick's solitary moment of quality.