Michaelis, born in Haynau in the Prussian Province of Silesia, grew up in Frankfurt (Oder). He studied jurisprudence at the University of Breslau, the University of Leipzig and the University of Würzburg from 1876 to 1884, becoming a Doctor of Laws.

From 1885 to 1889 he lived and worked in Tokyo in Japan as a law professor of the Law School of the Society for German Sciences.

After his return to Germany he became a member of the Prussian administration. In 1909 he won appointment as undersecretary of state to the Prussian Treasury in Berlin. From 1915 onwards he headed the Reichsgetreidestelle, an office responsible for the administration of Prussian corn and wheat in World War I.

After the Reichstag and the High Command forced the resignation of Theobald von Bethmann Hollweg on July 14, 1917, Michaelis became Chancellor of Germany as well as Minister President of Prussia. He remained in this position until October 31, 1917, when he was forced to resign after coming under fire for refusing to commit himself by endorsing a resolution passed by the Reichstag favoring peace without annexation or indemnities. In addition, he was increasingly seen as a puppet of Paul von Hindenburg and Erich Ludendorff of the General Staff.

Michaelis attempted to retain his role as Prussian Minister President, without success. From April 1, 1918 to March 31, 1919, he served as Oberpräsident of the Prussian province of Pomerania. After the end of World War I, he cooperated with the local workers' and soldiers' council. Nevertheless, the Socialist dominated government of Prussia soon replaced him.

After his dismissal, Michaelis worked in the fields of economic lobbying, in student organizations, in the synod of the Evangelical Church of the old - Prussian Union and became a member of the monarchist German National People's Party (DNVP). In 1921, he published his memoirs, Für Staat und Volk. Eine Lebensgeschichte.

Georg Michaelis died on July 24, 1936 in Bad Saarow - Pieskow (Brandenburg) at the age of 78.