Kearney, the 20-year-old Academy forward who stands at 6ft 5in, is a former Mount Temple Comprehensive pupil and has represented Ireland at Under-18, Under-20 and Colleges level.
He earned his first senior cap for Connacht against the Ospreys this season and has appeared five times for the westerners since then.
The other change in the pack sees Adrian Flavin come back in for Ethienne Reynecke at hooker. With over 117 caps Flavin is one of Connacht's most experienced players and even allowing for Kearney's youth, the starting forwards boast 765 caps between them
There are three changes to Connacht's starting back-line. Frank Murphy makes way for Paul O'Donohoe at scrum half, Brian Tuohy replaces Fetu'u Vainikolo on the right wing and Connacht's newest signing Kyle Tonetti takes over from the injured David McSharry in midfield.
Tonetti joined Connacht from Sale Sharks earlier this season and steps in for McSharry who required stitches to his chin following the St. Stephen's Day clash with Munster.
CONNACHT (v Leinster): Gavin Duffy (capt); Brian Tuohy, Eoin Griffin, Kyle Tonetti, Tiernan O'Halloran; Niall O'Connor, Paul O'Donohoe; Brett Wilkinson, Adrian Flavin, Ronan Loughney, George Naoupu, Mike McCarthy, Michael Kearney, Johnny O'Connor, John Muldoon.
Replacements: Ethienne Reynecke, Denis Buckley, Dylan Rogers, Eoin McKeon, Thomas Anderson, Frank Murphy, Matthew Jarvis, Henry Fa'afili.