Adidas currently produce all of the Hammers' official kits but the change will take place ahead of the club's final season at Upton Park before their move to the Olympic Stadium for the 2016/17 campaign.
A link-up with Umbro has long-been in the pipeline and Press Association Sport understands the new deal is twice the size of their technical partnership with Adidas, which was announced in 2013.
With the move to the Olympic Stadium on the horizon, West Ham vice-chairman Karren Brady was pleased to seal a new partnership.
"As we approach two historic seasons for West Ham United, we are delighted once again to team up with Umbro," she told the club's official website.
"(They are) a company which - like West Ham - is steeped in the heritage of English football but also a fast-growing global brand with an exciting future ahead.
"It is especially fitting that - during our final season at the Boleyn Ground - our players and fans will wear a brand synonymous with one of the finest moments in West Ham's rich history: England's 1966 World Cup triumph."
Source : PA
Source: PA