Maxus had already handled media for Huawei in large parts of Europe and China.
Sources say the business is worth £20 million in the UK this year.
Huawei added Havas London to its global creative roster last month. The agency is working on the creative development of global launch campaigns and other above-the-line activity.
Dare handled the UK creative account before Havas London. It won the business from Let Us Create in 2014.
A spokeswoman at Huawei said: "Maxus has been appointed as one of Huawei’s London-based agencies with a UK media and planning scope of work."