Hamsik put pen to paper on fresh terms with the Azzurri tonight, extending his current deal until 2018.
Napoli president Aurelio de Laurentiis used Twitter to confirm that the Slovakian player had signed a new deal earlier this evening.
De Laurentiis tweeted: "With Hamsik is a perfect marriage. Great man, great professional, great player that honors the shirt of Napoli
"It is a shirt that Marek is happy to honour. We have renewed his contract, extending it until 2018."
A final picture message of the evening from the Napoli chief then showed him sharing a glass with Hamsik, with an accompanying message which read: "Marek and I toast to that renewal."
The 26-year-old has made more than 260 appearances since joining Napoli in 2009, scoring 70 goals in all competitions.