The 19-year-old is a left-back who plays for Legia Warsaw in Poland’s Ekstraklasa and is already a regular for the 14-time champions.
Unless of any twists, Karbownik will become the most expensive export from the Polish league.
That record is currently held by Radoslaw Majecki, who Monaco paid €7m to sign from Legia in January.
The fee for Karbownik will be similar, but slightly higher and Napoli are ready to hand the teenager a five-year deal worth €800,000-per-season.
Karbownik made his debut in the Polish top-flight last season, delivering seven assists in 28 appearances.
He is also capable of playing an a midfield ‘regista’, which is what Napoli may have in mind for him.