August Philipp was Prince-Bishop of Speyer and sovereign Lord zu Gemen from 1771 until 1797.
At the age of 8 years, on 6 December 1729 Damian August Philipp Karl von Limburg-Stirum pronounced his vows.
One year later, on 6 December 1730, he was made Domicellar of Speyer by his uncle prince-bishop Damian Hugo Philipp von Schönborn.
Prince-bishop Damian August Philipp Karl von Limburg-Stirum died in Passau on 22 February 1797 in Freudenhain castle.
His heart was however brought to Bruchsal on 21 March 1797 and placed in a silver urn in the tomb of the Prince Bishops in St. Peter's church.