Pompey have taken up the option to extend Jay Mingi’s contract with the club.
The 21-year-old midfielder signed for the Blues back in September after impressing during a pre-season trial period.
He was soon sent out on loan to National League outfit Maidenhead in order to gain some more first team experience.
Mingi returned at the turn of the year and made his Pompey debut from the bench in a 4-0 rout of Accrington.
Blues boss Danny Cowley said: “Jay is a young player on an upward curve and had a really positive first half of last season on loan at Maidenhead.
"We see further growth in him, so we look forward to supporting Jay in his development."
“That was unfortunately curtailed by a dislocated shoulder and we had many different options for him – both in the National League and League Two – in January.
“But we decided to keep him as part of our group and he benefitted from training with us on a consistent basis.
“We were able to work on different areas of his game – particularly in possession and his ability to seek a pass.
“It was great to see him make his Football League debut for us and we see further growth in him, so we look forward to supporting Jay in his development.”
Mingi made a total of three appearances for Pompey last season and previously turned professional with Charlton after a spell in West Ham’s academy.