The 23-year-old arrives following his release by Huddersfield at the end of last season and will compete with Will Norris for the No1 jersey at Fratton Park.
His move means the Blues have now signed 12 players during the current transfer window, with a new No8/10 also wanted by John Mousinho before September.
However, Pompey haven’t been the only ones adding to their squad over the past week. Here’s what strengthening their League One rivals have been doing since Sunday.
17. Kell Watts (Wigan)
Club just left: Newcastle. Transfer details: Loan deal. Photo: Michael Regan
18. Finn Talley (Peterborough)
Club just left: Brighton. Transfer details: Free transfer. Photo: Matt McNulty
19. Stanley Mills (Oxford United)
Club just left: Everton. Transfer details: Loan deal. Photo: Matt McNulty
20. Freddie Potts (Wycombe)
Club just left: West Ham. Transfer details: Loan deal. Photo: David Rogers