The Basset & Gold logo will now feature on the left sleeve of West Ham's shirts for the first team, Academy and Premier League 2 sides. They will also become the Hammers' official eSports partner.
West Ham are pioneers in eSports, as they became the first British football team to announce an eSports player in 2016, with the London Stadium hosting the first ever eSports tournament involving professional clubs.
“I am delighted to announce our partnership with Basset & Gold and I am extremely excited about working together going forward," said West Ham Vice-Chairman Karen Brady.
"What really appealed to us was their commitment to working and engaging with our fans in east London and the local community.
“Our fans are at the heart of everything we do and we wanted to partner with someone who understands that and mirrors that commitment in their own work.
"Both partners are determined to achieve success next season and we cannot wait to launch our partnership through some incredible activations for our fans.”
A Basset & Gold spokesperson said: “we are delighted to become a partner of West Ham United Football Club. We found West Ham United to stand out from the others in the way they treat their fans and their community, which is also ours."