Northern Ireland international Gavin Whyte has joined Pompey on a 3-year deal.
The 27-year-old makes the switch from South Wales to the South Coast following his departure from Cardiff City at the end of the 2022/23 season.
Whyte has experience not only getting out of League One but winning it too, helping Hull City to the title in 2021 whilst on loan from Cardiff.
On the international stage, the winger has received 28 caps, scoring 5 goals.
John Mousinho told club media: "Out of all the player's we've signed, he's the first one that I actually played with and he's a great character."
Whyte made 36 league appearances for Oxford United during his one and only permanent season with the club in 2018/19, scoring on his U's debut in a Carabao Cup victory over Coventry City.
He would return to the Kassam Stadium on loan for the 2021/22 campaign.
The Blues' head coach continued: "He had an outstanding first season when he came over to Oxford from Northern Ireland and went to Cardiff off the back of that.
"He's someone that we believe will really excite everybody at Fratton Park and be an excellent addition to our side."
Gavin Whyte becomes Pompey's 8th signing of the summer transfer window, following the arrivals of Will Norris, Conor Shaughnessy, Christian Saydee, Terry Devlin, Anthony Scully, Ben Stevenson and Jack Sparkes.