Schmidt, aged 44, has been backs coach in Clermont in combination with fellow New Zealander Vern Cotter and during his spell with the French outfit the club has reached three successive French Championship finals.
He previously coached the Auckland Blues in the Super 14 and Bay of Plenty to win the prized Ranfurly Shield.
A former assistant coach to the New Zealand Schools team for four seasons, he is also a former school headmaster.
In addition, Schmidt spent a year in Ireland as a player in the early 1990s when he assisted the Mullingar Club in Leinster.
Leinster will not be making any further comment and will announce the remainder of the new coaching team in the coming months.