Academy duo Lewis Stockford and Lewis Tallack have signed one-year professional contracts.
The pair have both completed a two-year scholarship programme with Pompey.
Stockford is an 18-year-old midfielder who comes from Portsmouth, while Tallack – also 18 – is a defender who was born in Luton.
Academy manager Andy Awford said: “They’ve both worked extremely hard since I’ve been at the club and deserve the opportunity to progress.
“Now they’ve got another year at the club to see if they can move up to the next level.”