Lupoli (left) has enjoyed a successful loan spell at Derby

The 19-year-old, who joined the Gunners in 2004 from Parma but made just one Premiership appearance for them, has agreed a five-year deal.

Lupoli is midway through a season-long loan spell at Championship high-flyers Derby County.

He had shown an interest in a move to Napoli and even hinted he would consider staying with Derby if they were to be promoted to the Premiership.

But the Italy Under-21 international, who scored on his debut for Pierluigi Casiraghi's men in their friendly against Luxembourg in December, has decided to join Serie A side Fiorentina instead.