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.
9. Joe Anderson (Shrewsbury)
Club just left: Sunderland. Transfer details: Loan deal. Photo: Frank Reid
10. Corey O'Keeffe (Barnsley)
Club just left: Forest Green Rovers. Transfer details: Permanent deal. Undisclosed fee. Photo: Alex Burstow
11. Tayo Edun (Charlton)
Club just left: Blackburn Rovers. Transfer details: Permanent deal. Undisclosed fee. Photo: Lewis Storey
12. Tristan Crama (Bristol Rovers)
Club just left: Brentford. Transfer details: Loan deal. Photo: Harriet Lander