The 30-year-old's future at Anfield has been in question ever since the arrival of Simon Mignolet from Sunderland last month in a deal reported to be worth £9 million.
Rodgers had initially talked up competition for places but also expressed concerns about the financial implications of having the two keepers on the wage bill and, following a successful medical at the Stadio San Paolo on Wednesday, a loan move has now been finalised.
|8/1||Napoli are 8/1 with Bet365 to win Serie A
"On the football side, we have to protect the team and, at that stage, we started our search for another goalkeeper.
"As events transpired, that move [for Reina] didn't happen and it left us with two very good goalkeepers. Both would have been fighting for the No.1 position.
"It's decided he will go to Napoli and we've got two very good goalkeepers still at the football club [Mignolet and Brad Jones].
"As a senior goalkeeper, he needs to be playing. It's a very important year for him with the World Cup next year. It wouldn't have served any purpose, both for the club and him personally, if he'd been the one missing out."
Despite clinching 25-year-old Mignolet on a long-term contract, Rodgers has, however, not completely closed the door on Reina's Liverpool future, adding: "We'll review it after the loan finishes."