China’s top-selling smartphone maker Xiaomi has raised $1.1bn in a venture capital funding round valuing it at $45bn, in a big vote of confidence in the fast-growing company.

The valuation makes Xiaomi the world’s most highly valued technology start-up, with the four-year-old business surpassing Uber’s $40bn valuation after the ride-hailing app closed a $1.2bn fundraising round earlier this month. It also values the company at more than three times that of Hong Kong-listed Lenovo, which is running neck-and-neck with Xiaomi for leadership in the Chinese smartphone market.

Lei Jun, chief executive, said on his blog on Weibo, China’s equivalent of Twitter, that the valuation was a “watershed” marking the beginning of a new stage in development. The valuation of the company, which has previously said it will not launch an initial public offering before 2018, is more than four times the $10bn value it was given after its last funding round in August 2013.