Gerry Davis' side secured the points against an ill-disciplined and nine-men San Marino with second-half strikes through the Rockmount duo of Luke Casey and Eoin Murphy.
It was a combative tie at the Albena Sports Complex but Ireland deserved huge credit for keeping their discipline while their opponents saw their captain and goalkeeper sent off during the second-half.
Ireland started with seven UEFA Regions Cup debutants and after a nervy opening exchange, it was Gerry Davis' side who began to impose themselves on the tie as Eoin Murphy had a shot blocked in the sixth minute.
San Marino had their best opportunity of the match with a quarter-of-an-hour gone, when Elia Ciacci failed to connect as the ball flashed across goal after a teasing cross by Matteo Semprini.
Ireland looked dangerous from set-pieces and Jack McMullan of Home Farm was a constant threat as he ventured forward from his defensive duties. Eoin Hayes of Newmarket Celtic had a shot beaten away by Gentilini in the San Marino goal in the 23rd minute but the stop-start nature of the occasion was counterproductive to any free flowing football.
As the game approached the half-way mark, Luke Casey saw his goal-bound effort blocked away with the game goalless at the break.
San Marino suffered a major blow in the 64th minute when captain Angelini saw his second yellow to reduce the opponents to ten men and they were further reduced in number just four minutes later when goalkeeper Gentilini was dismissed for a poor challenge on Murphy.
As their numerical advantage began to create openings, Ireland finally took the lead with 20 minutes remaining. Stephen Chambers was able to supply a fantastic cross from the right and Luke Casey headed back across goal to score.
Eight minutes later, the points were secure when Eoin Murphy was found clean through in the area and he rounded the keeper to finish and complete the scoring.
Ireland's next match is on Friday, October 28 against Romania knowing that victory will give them a great chance of progression with one game to go.
Republic of Ireland: Brendan O'Connell (GK, C); Lee McColgan, Adam Crowley, Jack McMullan, AJ O'Connor, Jimmy Carr, Eoin Hayes, Stephen Chambers, Luke Casey, Chris Smith, Eoin Murphy. Subs: Sam Burgess (Eoin Hayes 77), Aaron Humphries (Luke Casey 83), Nathan Broderick (Jimmy Carr 84), Deiric Hyland (Eoin Murphy 88).
San Marino: Fabio Gentilini; Michael Parma, Frederico Pescaresi, Luca Angelini, Nicholas Arrigoni, Matteo Semprini, Marseljan Mema, Lorenzo Dormi, Andrea Comuniello, Elia Ciacci, Matteo Gaiani. Subs: Luca Olivieri (Communiello 58), Denis Broccoli (Semprini 67), Matias Colagiovanni (Dormi 82), Armando Senja (Gaiani 84).
Referee: Zaven Hovhannisyan (Armenia)