The Bismarck-Roon Cabinet formed the Prussian State Ministry appointed by King William I, and his successors Frederick III, and William II, from September 23, 1862, to March 30, 1890.

After the previous government failed due to the Prussian constitutional conflict with the liberal majority in the chamber over the state parliament's participation in military affairs and fundamentally over the parliamentarization of Prussia, William I appointed a conflict minister, Otto von Bismarck.

Bismarck successfully ended the constitutional conflict for the crown through the successes of his policies in the wars against Denmark in 1864 and Austria and its German allies in 1866, which enabled him to have the subsequent tax approval in the Indemnity Act (Indemnitätsgesetz) approved by the House of Representatives as a reconciliation offer to the Liberals.

Albrecht von Roon replaced Bismarck as Prussian Prime Minister in 1873 in order to relieve the German Chancellor.

The separation proved to be unsuccessful so Bismarck returned to the Prime Minister's office at the end of 1873.