Connacht's Fionn Carr was also among those recognised when he was awarded the IRUPA Volkswagen Try of the Year for his 70-yard effort in the Magners League away to the Scarlets.
Nacewa was his typical humble self after receiving the award, saying: "This is the first time I've received an award in any country which has been voted for by my peers and I am overwhelmed to be honest that the other players in Ireland have chosen me.
"I'd like to thank all my team-mates in Leinster who have made my job a lot easier."
Nevin Spence of Ulster picked up the IRUPA Nature Valley Young Player of the Year following his senior breakthrough with the province this season, which has included a Heineken Cup try against Bath.
Leinster hooker Richardt Strauss, who has extended his contract with the province until 2013, collected the IRUPA Nokia Unsung Hero award.
Joining Ireland's heroes in the Bord Gáis Energy IRUPA Hall of Fame was Leinster legend Malcolm O'Kelly.
Sean O'Brien, who has been a regular man-of-the-match winner for Leinster this season, was also announced as the Bord Gáis Energy IRUPA Supporters' Player of the Year. The award was voted for by listeners of Newstalk106-108FM.
Omar Hassanein, CEO of IRUPA, said: "Winning an IRUPA award is the highest honour a player can receive. Those players can take great satisfaction from the fact that they have the total respect of those who they play with and against.
"Congratulations to all those nominated and in particular to Isa, Fionn, Richard, Nevin, Brian, Sean and 'big Mal' in winning what are the most sought after awards in Irish rugby."
Commenting on tonight's awards, John Mullins, the CEO of Bord Gáis, said: "Many congratulations are due to Isa on being honoured with the Bord Gáis Energy IRUPA Players' Player of the Year.
"Leinster have reached their second Heineken Cup final in three years and Isa made an outstanding contribution to this feat on Saturday and indeed the run-in to that victory over Toulouse.
"In a World Cup year it's encouraging to see Irish rugby continuing to flourish and I'd like to acknowledge the great work IRUPA does in supporting the players who make this possible.
"The turnout of top stars tonight is clear testament of the high regard in which they hold the organisation and Bord Gáis Energy is proud to be a part of that."
The O2 Rugby Moment of the Year was also announced at the awards with Ireland captain Brian O'Driscoll taking home the award for his try against England which broke the Championship try-scoring record which stood for 78 years.
2011 BORD GÁIS ENERGY IRUPA AWARD WINNERS:
BORD GÁIS ENERGY IRUPA PLAYERS' PLAYER OF THE YEAR -
Winner: Isa Nacewa (Leinster)
Keith Earls (Munster)
Isa Nacewa (Leinster)
Sean O'Brien (Leinster)
IRUPA NOKIA UNSUNG HERO OF THE YEAR -
Winner: Richardt Strauss (Leinster)
Willie Faloon (Ulster)
Richardt Strauss (Leinster)
IRUPA NATURE VALLEY YOUNG PLAYER OF THE YEAR -
Winner: Nevin Spence (Ulster)
Conor Murray (Munster)
Rhys Ruddock (Leinster)
Nevin Spence (Ulster)
IRUPA BORD GÁIS ENERGY HALL OF FAME -
Inducted: Malcolm O'Kelly (Leinster)
IRUPA VOLKSWAGEN TRY OF YEAR -
Winner: Fionn Carr (Scarlets v Connacht, Magners League)
Fionn Carr (Scarlets v Connacht, Magners League)
Craig Gilroy (Ulster v Cardiff Blues, Magners League)
Isa Nacewa (Leinster v Leicester Tigers, Heineken Cup)
IRUPA BORD GAIS ENERGY SUPPORTERS' PLAYER OF THE YEAR -
Winner: Sean O'Brien (Leinster)
IRUPA O2 RUGBY MOMENT OF THE YEAR -
Winner: Brian O'Driscoll - Record breaking 25th 6 Nations Championship Try Against England.
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