His uncle Joseph Clemens, elector and archbishop of Cologne saw to it that Klemens August of Bavaria received several appointments in Alt-Oetting, diocese Regensburg and at the Prince-Bishopric Berchtesgaden and he soon received papal confirmation as bishop of Regensburg, later Cologne.
He was Archbishop of Cologne, Prince-Bishop of Münster, Hildesheim, and Osnabrück, and a Grand Master of the Teutonic Order.
He was the son of Maximilian II Emanuel, elector of Bavaria.
His family was split during the War of the Spanish Succession and was for many years under house arrest in Austria.
His brother KlemensAugust of Bavaria, later archbishop and elector (Kurfürst) of Cologne, who mostly sided with the Austria Habsburg-Lorraine side during the Habsburg successions, did cast his vote for him and personally crowned him emperor at Frankfurt.
The Wittelsbach family were the ruling dynasty of the German state of Bavaria from 1180 to 1918 and of the Rhine Palatinate from 1214 until 1805; in 1815 the latter territory was incorporated into Bavaria, which had been a kingdom since 1806.
The family provided two Holy Roman Emperors: Louis IV (1328-1347) and Charles VII (1742-1745), and for half a century until 1373 controlled Brandenburg to the north-east.
Maximilian II Emanuel, elector of Bavaria (1662 - 1726)