In the course of their struggle against the competing Welfen family, he was given the formerly Welfish Bavaria as a fief by Emperor Conrad III.

He managed to maintain his position there, as his brother Otto was Bishop of Freising there.

The most important measure of his short reign was the Exchange of Mautern entered into with the Bishop of Passau in 1137.

The bishop was given the St. Peter's Church in Vienna, while the Margrave received extended stretches of land from the bishop outside the city walls, with the notable exception of the territory where a new church was to be built, which was to become St. Stephen's Cathedral.

Leopold died unexpectedly at Niederaltaich Abbey in Bavaria and was succeeded by his brother Henry.