An Academy of Football player since he was five-years-old, Casey signed professional terms with West Ham United in summer 2022.

The defender was involved in two first-team senior squads in 2022/23, making his senior debut in a 3-0 victory against FCSB in the UEFA Conference League, before sitting on the bench for a Premier League London derby against Tottenham Hotspur.

Casey would make 18 appearances in all competitions at U21 level, while the defender also continued to represent the U18s, featuring eleven times during the side’s U18 Premier League South winning campaign, scoring three goals. He also started all six FA Youth Cup matches for the U18s and scored a towering header in the final.

Another impressive campaign followed as Casey captained the U21s to a second place finish in the Premier League 2 regular season. During the 2023/24 campaign, he also travelled with the first-team squad 14 times across all competitions, making his Premier League debut in the Hammers' last home game of the season, a 2-1 victory over Luton Town.