George, Crown Prince of Serbia, was the eldest son of King Peter I of Serbia and his wife, the former Princess Ljubica of Montenegro. He was the older brother of King Alexander I of Yugoslavia.

Peter I was King of Serbia from 15 June 1903 to 1 December 1918. On 1 December 1918, he became King of the Serbs, Croats and Slovenes, and he held that title until his death three years later. Since he was the king of Serbia during a period of great Serbian military success, he was remembered by Serbians as King Peter the Liberator and also as the Old King.