In 1436 he became provost of St Guido's church in Speyer and then in 1437 a canon of the bishopric of Cologne.
From 1438 to 1439 he studied at the university of Heidelberg and in 1440 he became a canon at Strasbourg Cathedral.
Conrad of Bussnang, bishop of Strasbourg, made Rupert his coadjutor in 1439 and granted him a lifelong pension in 1440.
Politically he favoured the Electoral Palatinate and concluded an alliance with Frederick I.
He modernized his prince-bishopric along the lines of contemporary secular states but his high demands for control met with resistance.