Kenny made his debut against the Sharks last October.
JJ Kenny has signed his first senior contract with Leinster.
The 22 year old made his debut against the Sharks last October, and has since gone on to score 11 tries for the province.
There are also extensions for forwards Thomas Clarkson and Alex Soroka.

Ireland Face Must-Win Kosovo Clash After Narrow Defeat To Austria
Kildare Trio Feature As Ireland Overcome Fiji In Nations Championship
Kildare's Sean O'Haire Kicks Dramatic Last-Minute Winner In American College Football
Sunday Morning Sports Update
Milltown Through To Leinster Intermediate Semi-Finals After Victory Over Meath Champions
Sarsfields Leinster Championship Campaign Ends After Heavy Defeat To Cuala
More Than 20 Horses Withdrawn At Cheltenham Over Ground Conditions