After returning to Berlin from his first trip to Italy in 1805, he started to earn his living as a painter. When he saw Caspar David Friedrich's painting Wanderer above the Sea of Fog at the 1810 Berlin art exhibition he decided that he would never reach such mastery of painting and turned to architecture.
After Napoleon's defeat, Schinkel oversaw the Prussian Building Commission. He was responsible for reshaping Berlin into a representative capital for Prussia and oversaw projects in the expanded Prussian territories from the Rhineland in the west to Königsberg in the east, such as New Altstadt Church.
From 1808 to 1817 Schinkel renovated and reconstructed Schloss Rosenau, Coburg, in the Gothic Revival style.
His most famous buildings include Neue Wache (1816–1818), National Monument for the Liberation Wars (1818–1821), the Schauspielhaus (1819–1821) at the Gendarmenmarkt, which replaced the earlier theatre that was destroyed by fire in 1817, and the Altes Museum ('old museum') on Museum Island (1823–1830). He also carried out improvements to the Crown Prince's Palace.