Amerikanos was born in Nikaia, Piraeus in 1942 and started his career at the YMCA Nikaia. He transferred to AEK where, as their captain, he led the team to glory including the 1964, 1965, 1966 and 1968 Championships, a trip to the final four of the European Cup of Champions in 1966 at Bologna Italy and the European Cup-Winners Cup on April 4, 1968. In that particular final at the Kallimarmaro, Amerikanos scored 29 points in AEK's 89-82 victory over Slavia Prague before 80,000 fans.
The low point of Amerikanos' career came after an international match when he threw his shirt in disgust at his performance. Newspapers of that period described him as "unpatriotic" and even "anthellenic", charges Amerikanos vehemently denied.
Giorgos Amerikanos had a total of 67 caps scoring 1,055 points with the National Basketball Team of Greece.