Callum Marshall joined West Ham United's Academy of Football in January 2022, when he signed from Northern Irish club Linfield.

The County Antrim-born striker made an immediate impact, scoring in his first four U18 Premier League matches and ending the 2021/22 season with nine goals in 16 appearances.

Marshall's form continued into the 2022/23 campaign, as he scored 23 goals in 24 matches in all competitions to help the U18s win the U18 Premier League South and FA Youth Cup double. The forward scored four goals in the Youth Cup, including one in the 5-1 victory over Arsenal in the final at Emirates Stadium.

Marshall also featured times for the U21s, scoring his first goal for Mark Robson’s side in a Premier League 2 draw away to Blackburn Rovers in October 2022. 

The Glengormley native received a first senior Northern Ireland call up, and a debut, and then saw his late goal ruled out by VAR in a 1-0 UEFA Euro 2024 qualifying defeat in Denmark in June 2023.

Marshall's prolific form continued into the 2023/24 season as he netted 19 times in 14 games, including three in four EFL Trophy appearances, before making his first-team debut for West Ham as a substitute in the FA Cup third-round replay defeat at Bristol City on 16 January 2024.

The striker signed a new contract until summer 2027 and was loaned to EFL Championship club West Bromwich Albion in late January 2024.

After making his EFL debut and three appearances from the bench, Marshall reached an agreement to return to the Hammers in April 2024 to enable him to play for the U21s and continue his development with his parent Club.