The Irish booked their place in the Euro 2012 play-offs courtesy of some good fortune as both sides were reduced to 10 men in Dublin
Armenia had their goalkeeper Roman Berezovsky sent off on 26 minutes after the 37-year-old was harshly ruled to have used his hand to control the ball outside of his area. The home nation were then gifted a goal when Valrei Aleksanyan accidentally put the ball into his own net three minutes before the break.
Richard Dunne scrambled over the line to make it 2-0 on 59 minutes before Henrik Mkhitaryan's strike three minutes later proved to be just a consolation. Kevin Doyle then saw a second-yellow card on 81 minutes with both sides ending the game with 10 men.
The result, combined with Russia's 6-0 victory over Andorra, means Giovanni Trapattoni's side finish in second place in Group B, two points behind the eastern European nation who top the table.
After a slow start to the game, the Republic of Ireland created the first clear chance on 12 minutes. Simon Cox's bustling run saw the striker tee up Kevin Doyle, who wasted a glorious chance to open the scoring when he struck the ball straight at Roman Berezovsky from 12 yards out.
That was to be the veteran goalkeeper's last action of the game as he was controversially sent-off in the 26th minute. Cox emerged one-on-one with Berezovsky who charged quickly out of his goal and was adjudged to have handled the ball outside of his penalty area. However, replays showed the 38-year-old chested the ball to safety instead of using his hand.
Armenia reacted well to going down to 10-men yet shot themselves in the foot when they conceded a shocking own goal on 43 minutes. Damien Duff's low cross along the six-yard box was missed by the stretching Doyle, only for Valeri Aleksanyan to inexplicably poke the ball into the corner of the net to give the home nation the lead at half-time.
The Republic of Ireland started the second-half brightly and doubled their lead on 59 minutes. Aiden McGeady showed some excellent footwork on the right-wing before whipping an inviting cross into the box, with Richard Dunne bundling the ball over the line from six yards out.
However, Armenia refused to accept defeat and grabbed a goal back three minutes later. Yura Movsisyan's cut back found Henrik Mkhitaryan on the edge of the box who stroked the ball into the corner of the goal, the first time the Irish defence had been breached in nine games.
Ireland were made to sweat a little late on when they were also reduced to 10 men, Kevin Doyle being given his marching orders for picking up a second yellow card for leading with his elbow against Aleksanyan.
The away nation pressed to get back level but were unable to cause Ireland's back line any real trouble as the home team picked up all three points.
Trapattoni's men will now be placed into Thursday's play-off draw where they will find out who they will play in the two-legged tie, with the first leg to be played on the 11 and 12 November, and the return legs on 15 November.