Roso was born in Split, Croatia, (then as SR Croatia, part of SFR Yugoslavia), in a family, whose grandfather was of Italian origins. He played for NK Zagreb between 1994 and 1996 before moving to Israel.
Roso enjoyed great success in the decade he played for top teams in Israel, including a campaign in the UEFA Champions League with Maccabi Haifa. He's acknowledged as being among the very best foreign players ever to play in the Israeli Premier League, as well as for his lively personality and prominent sense of humour.
Roso's form in 2004 got him called up for Croatia, so he played for his birth country at Euro 2004. It was only later, in 2005, that he finally obtained Israeli permanent resident status. However he could never play for the Israeli national team, since he had already played for Croatia.
Roso speaks fluent Hebrew, and stated numerous times that he plans on coming back to live in Israel at the end of his football career.
In media, his name is often Italianized to Giovanni Rosso, due to its origins.
His return to Hajduk Split was ruined by injuries. He only ended up playing four times in the Croatian first league. He retired from club football in June 2009. It was reported that he is to take up a coaching job at Hajduk.