Before playing for Arsenal, his contract at Italian side Parma had expired. Achieving an Arsenal contract by way of a scholarship, the Gunners repaid Parma with a 200,000 pound sum by way of compensation.

His debut first-team appearance was in a match against Manchester City in the Carling Cup on October 27, 2004. His next match, against Everton in the same competition, brought him his debut goals for the club, scoring two of Arsenal's three goals in the 3-1 victory on November 9. He also played in the match against Manchester United which saw Arsenal's exit from the competition after a 20-second goal from David Bellion. He was Arsenal's top scorer at youth/reserve level in 2004-05, with 27 goals in 32 appearances.

At the start of the 2005-06 season, it was rumoured Lupoli would be loaned to Ipswich Town, although Blues manager Joe Royle later ruled out any such move. He remained at Arsenal, and although a reserve player, has figured in the Gunners' 2005-06 Carling Cup campaign.