The Azzurri have confirmed the 26-year-old Colombia international will undergo a medical on Thursday before the arrangement is finalised.
A statement on sscnapoli.it read: "Napoli have reached an agreement with Udinese that will see Pablo Armero wear the blue shirt.
"The left winger will arrive on loan with the option to buy out half of his contract at the end of the season.
"Armero will undergo his medical tomorrow, after which the deal will be made formal."
Armero joined Udinese from Palmeiras in 2010 and has made 69 league appearances for the Bianconeri, scoring two goals.