The 26-year-old featured in all nine of his side's European matches this season, including Saturday's final against Ulster.
Discussing the award, Kearney was quick to praise the contribution of his teammates.
"While I am delighted with the recognition, an individual player is powerless without the support of his teammates," he said.
"So I owe this to the Leinster squad, to the management and to all the backroom staff at the club."
Kearney was recently named in the Ireland squad that will tour New Zealand next month.