Struggling between his Polish subjects and the Prussian authorities, Radziwiłł found himself with little power, as effective power was executed by Oberpräsident Joseph Zerboni di Sposetti and the district governors heading the Regierungsbezirke of Posen and Bromberg.
From 1813 to 1919, it was administered by the Prussian Province of Lower Silesia in the political subdivision Regierungsbezirk Breslau.
They were established in the course of the Stein-Hardenberg Reforms from 1815 to 1818 at an intermediate level, between the higher provinces and the government districts (Regierungsbezirke), and the lower municipal governments (Gemeinden).
Until 1919 Garnsee had belonged to Kreis Marienwerder in the administrative district of Regierungsbezirk Marienwerder in the province of West Prussia, from 1919 to 1939 in Regierungsbezirk Westpreußen of the province of East Prussia and from October 26, 1939, to 1945 in Regierungsbezirk Marienwerder of the province of Reichsgau Danzig-West Prussia.
It belonged to the government region (Regierungsbezirk) Cöslin (later Köslin) in the Prussian province of Pomerania, and comprised rural regions as well as the towns of Colberg and Cörlin.
The western half of Lower Silesia was incorporated into Regierungsbezirk Liegnitz (Legnica), the adjacent Upper Silesian land in the east into Regierungsbezirk Oppeln (Opole).