Being a big athletic talent, he distinguished himself in track and field sports. But football was his big passion. He played for Ethnikos G.S. Athens and when his later club Panellinios decided to discontinue its football team, Kalafatis together with 40 other athletes broke away and established in February 1908 the first team of Panathinaikos, named Podosfairikos Omilos Athinon (Football Club of Athens).[2] Kalafatis appointed the Englishman John Cyril Campbell as coach for the new team. It was the first time that a foreigner was appointed as the coach of a Greek team.
Apart from Giorgos Kalafatis, other establishing members of POA were: his brother Alexandros, who was the first president, Emmanouel Chrysis, Dimitris Doukakis, Periklis Mpoumpoulis, Vasileios Granitsas, Mantzakos, Papageorgiou, Gaetas, Demertzis, Stavropoulos, Paschos, Misakian, Reppas, Sapounias and Garoufalias.[3]