A report on Napoli's official radio station said that the Slovakian was on his way to the city's Capodichino airport when the incident happened.
Two individuals were reported to have stopped his car, smashed one of the windows and, after waving a gun in the 25-year-old's face, made off with his watch and other valuables, before police arrived on the scene.
Hamsik is the latest Napoli player to have fallen victim to similar crimes in recent years.
Edinson Cavani and Valon Behrami have both been robbed in the last few years, while the partners of former Napoli forward Ezequiel Lavezzi - now of Paris Saint-Germain - and Hamsik have been mugged.
- Politics & Government
- Crime & Justice