Roubanis was born in 1932. He was a member of the great Panellinios club of the 1950s. At the same time he was a track and field athlete, a champion javelin thrower who held the Greek record with 65,98m (1952).
He finished his career with 25 caps in which he scored 275 points for National Basketball Team of Greece. He led Greece in Eurobasket 1951 with 61 points.