 Pröpper scored his first goal for Brighton in a 2–1 league defeat away against Leicester on 26 February 2019.Like the season prior, Pröpper made 4 appearances in the 2018–19 FA Cup where they went one step further, being knocked out in the Semi-final at Wembley Stadium against Manchester City in which Pröpper played in.Pröpper was again a regular in the squad for the Sussex club where their safety was secured on 4 May as a result of Cardiff City losing at home to Brighton's rivals, Crystal Palace.