The New Zealand champions held a 3-0 advantage from the first leg in Auckland but that began to erode quickly when Jimmy Tepa opened the scoring for AS Pirae just four minutes into the match.
The Tahitians doubled their lead five minutes before the break when talismanic striker Naea Bennett added a second to bring AS Pirae to within a goal of the visitors aggregate advantage.
AS Pirae – who defeated Auckland City FC 1-0 the last time the two teams met in Papeete nine years ago – looked in ruthless mood until Portuguese striker Joao Moreira pulled a goal back in the 45th minute.
The weight of that crucial away goal saw the momentum swing back Auckland City FC’s way but a spate of yellow cards for the visitors, combined with a superb midfield show by AS Pirae’s Marama Vahirua, left the Ramon Tribulietx-coached side anxious in the final moments of a tense match.
That tension spilled over in the final moments when Darren White – standing in for injured pair James Pritchett and John Irving – received a second yellow card from referee Issidore Assiene-Ambassa with five minutes left.
Despite their numerical advantage, AS Pirae were unable to crack open a stubborn Auckland City FC defence as the New Zealanders hung on for a 4-2 aggregate victory.
The win means Auckland City FC faces Amicale in the two-legged final, the second time the pair have contested an OFC Champions League final, the first back in 2011.
Amicale have won their last two encounters with Auckland City FC thanks to a pair of 1-0 victories registered on 31 March 2012 and 14 April 2014, the most recent of which was during the group stage of this OFC Champions League edition, a victory that saw the defending champions relying on results to see their way into the semi-finals.
The first of those two finals is scheduled for PVM Stadium in Port Vila on Saturday 10 May with a kick-off for 3pm local time.
The second leg takes place eight days later at Kiwitea Street in Sandringham, Auckland, on Sunday 18 May at 2pm local time.
The winner of the OFC Champions League advances to the FIFA Club World Cup Morocco 2014 in December.
Ends