Fluctuating between Berlin, Warsaw and Saint Petersburg, Radziwiłł developed the idea of making the province of South Prussia the nucleus of a renewed Polish kingdom, ruled by the Prussian king in personal union.

Instead Napoleon's expedition sparked the Greater Poland Uprising, which led to the establishment of the Duchy of Warsaw under the rule of King Frederick Augustus I of Saxony with Prince Poniatowski as war minister.

In the following years Radziwiłł retired to his city palace in Berlin and concentrated on regaining his family's vast estates in the Russian partition from the hands of Emperor Alexander I of Russia.

Shortly after the outbreak of the 1830 November Uprising in Russian Congress Poland led by his brother Michał Gedeon Radziwiłł, he was deprived of all powers, and the rule passed to Oberpräsident Eduard Heinrich von Flottwell.

His children with Louise were Germanized and never returned to Poznań; however, as owners of the Nieborów manor near Warsaw and huge family estates in today's Belarus, they paid frequent visits to other parts of Poland.

His palaces in Berlin (the later Reich Chancellery of Otto von Bismarck), Poznań and Antonin near Ostrów Wielkopolski were known for great concerts performed by one of the most notable musicians of his times.