The 18-year-old left-back who joins from Grasshoppers Zurich recently impressed in the UEFA European U19’s Championship and the Hammers moved quickly to secure his services as backup to current left-back Herita Ilunga.
“I am very happy to come here as it is a great club,” Daprela told the official site. “I saw the team play on television last season and it is a very good team. They have a great manager and it is good to be here.
“I want to play for the first team in the Premier League. I think I can learn a lot from the manger and people like Matthew Upson and Mark Noble and I am really looking forward to the season starting.”