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.

Germany Leave It Late To Reach World Cup Knockout Stages
Doris And O'Brien Ruled Out Of Ireland Tour
McIlroy Falls Off Pace At US Open
Netherlands Hit Five To Move Top Of Group F
Ireland And Munster Prop Oli Jager Retires At 30
Offaly's Grehan Claims Amateur Championship Crown
Kildare Ladies Set Up All-Ireland Quarter-Final Clash With Armagh