Nicole Barrett has put pen to paper on a new Pompey contract, subject to FA approval.
The defender's deal is one-year long, with a club option of an additional 12 months.
The 26-year-old joined Jay Sadler's side last July and appeared 30 times during the 2022/23 season.
She has scored two goals for the Blues, netting her first in the 2-0 National League victory over Watford in September.
Sadler said: "I’m delighted Nic has extended her stay with us. It's a fitting reward for the season she has had.
"After making the step up, she has been outstanding both on and off the pitch, showing real leadership in the most challenging moments.
"Her blend of physical and technical ability is a huge asset to our team and we believe the experience she gained last season will stand both us and Nic in good stead."
Barrett said: "It’s an honour to be a part of such a strong team and I’m grateful to be given this opportunity.
"I have so much confidence in the players and staff at Pompey, and I’m really excited for the season ahead with my team and the best fans in the league!"