The actor - who will also serve as investor and creative advisor - has become owner of a large part of the brand under the deal, reports TradeArabia.com.
Montegrappa CEO Guiseppe Aquila said: "I have had the pleasure of meeting Stallone on many occasions, including the 2009 Venice Film Festival, where he was recognised for his filmmaking with the 'Glory To The Filmmaker Award'.
"Stallone is much more than a friend - he is an icon and an artist and now, an integral part of Montegrappa's distinguished history."
Stallone is said to have become a fan of the company's writing instrument over 15 years ago.
