He studied law and economics at the Ludwig Maximilian University of Munich from 1951, gaining his license to practice as a lawyer in 1960.

From 1978 to 1987 he was in the private office of Franz-Josef Strauss while the latter was regional Minister for Federal and European questions.

He was also a member, at different times, of the coordination committee between the two chambers of the federal German parliament, and of the NATO Parliamentary Assembly.

Between 1987 and 1995 Schmidhuber was a member of the three Delors Commissions in Brussels, where he replaced Alois Pfeiffer, also from Bavaria.

After his retirement from the commission in 1995 Schmidhuber became a member of the Court of Directors of the Bundesbank (the German national bank).