Rowan Vine has impressed in his spell on-loan at Colchester United this season, prompting Portsmouth to renew the 21 year old's contract.
"We've agreed two more years with Rowan Vine. It's an extension to his existing contract" said chief executive Peter Storrie.
"The manager feels he is a player who has a future here" he continued.
Colchester are hoping Rowan Vine will continue on for Colchester next season on-loan, in what would be his third season in Division Two.