Marshall joins the Terriers on a season-long loan.
Huddersfield Town Sporting Director Mark Cartwright commented: “We’re delighted to welcome Callum to the club today.
“The loan market involving Premier League clubs and players has been slow so far in this window as they rightly take stock of how their players return from international competitions, but this opportunity has moved quickly over the last 48 hours and I’d like to thank everyone at West Ham United for the faith they have shown in us to look after one of their best prospects.
“We’ve been very clear about our desire to add to our forward options this summer, and Callum’s arrival on loan is an important piece of that puzzle. He has a prolific scoring record in Premier League 2 and the Bristol Street Motors Trophy, and we believe that can translate to First Team football.”
Huddersfield Town Head Coach Michael Duff added: “Callum is a player with clear talent and potential, and I’m looking forward to working with him.
“He’s an international teammate of Brodie Spencer and it’s clear from our talks that he shares a lot of his good characteristics; he’s very hard-working on the pitch, and he’s really driven to come here and score goals.
“I think he will really suit the style we want to play too, particularly as part of a front two. It adds another set of qualities to our forward options, which is exactly what you want as a Head Coach.”
Upon his arrival at Town, Callum Marshall said: “I’m happy to get this over the line; I can’t wait for the season to start.
“The aim is to show that I can do it in men’s football; that’s why I’ve come here. I know the club wants to be back in the Championship and there are expectations for us to challenge – hopefully we can deliver on it.
“I will always work hard for the team. Hopefully I can score a few goals and make a name for myself here!”