On 29 July 2005, Hislop rejoined West Ham as experienced cover along with Jimmy Walker for new signing Roy Carroll, allowing Stephen Bywater to go out on loan. Carroll started strongly but a back injury saw Hislop make occasional appearances through the season until Christmas. In January, Carroll's injury forced him to the physio's table once again, and Hislop stepped back into the fold as the starter (rotating with Walker). He featured in every FA Cup game as the team made its way to the final against Liverpool, keeping seven clean sheets in 27 appearances. The FA Cup Final finished 3–3 after a late equaliser from Steven Gerrard in the 91st minute. Hislop saving Sami Hyypiä's penalty was not enough for his team as Liverpool won the game 3–1 on penalty kicks after Anton Ferdinand missed the final West Ham spot kick of the day.