Pompey have signed right-back James Bolton on a three-year deal.
The 24-year-old will officially become a Blues player on July 1 when his contract with Shrewsbury expires.
Assistant manager Joe Gallen said: “He’s someone we’ve been tracking and has always played well against us over the past couple of seasons.
“James is solid, a dependable full-back and a positive character – he’s going to be a good addition to our squad.
“You need to defend, but also be able to provide service to the attacking players and we believe he can do both.
"We think we can improve him and that he can progress at this club, but he already brings a lot to the table."
“He was part of a Shrewsbury side that narrowly missed out on promotion, so he’s played at the top end of this division, which is where we expect to be next season.
“We think we can improve him and that he can progress at this club, but he already brings a lot to the table.”
Bolton began his senior career with Macclesfield and played for Halifax and Gateshead before joining Shrewsbury in 2017.
He made a total of 85 appearances for the Shropshire outfit and netted the winning goal in their League One victory at Fratton Park in January 2018.