Pompey have confirmed Adam Webster is moving to Ipswich, with Matt Clarke moving the other way as part of the deal.
Both deals will be completed on July 1.
Twenty-one-year-old Webster, who enjoyed his finest season at Fratton Park last term, has signed a three-year deal at Portman Road.
The Blues will received more than £500,000 for the player, along with Clarke, who was on loan at Fratton Park last season.
The central defender, who has also signed a three-year deal, made 34 appearances and scored once during that time – on occasions partnering Webster.
Clarke represents Pompey’s second signing of the summer, following last week’s arrival of Danny Rose from Northampton.