He replaces Denis Leamy.
Sean O'Brien will become Leinster's new contact skills coach, following the departure of Denis Leamy.
O'Brien will return to the province having brought an end to his playing career at London Irish in recent weeks.
Leamy is leaving the eastern province to return to Munster.
He'll fulfill the role of defence coach as part of Graham Rowntree's coaching ticket.

Sunday Morning Sports Update
Leinster Quarter Final wins for Athy, Sallins and Grange: Results
Naas Manager Mullally Resigns Carlow Position
Jannik Sinner Maintains Winning Run At The ATP Finals
Friday Morning Sports Update
Suncroft's Sam Prendergast To Start On Saturday Against Australia
Aviva Stadium Confirmed For Seven EURO 2028 Matches
Ireland To Play Australia In Saturday's Autumn Nation Series