DayOne Data Centers, a Singapore-based data center operator gearing up for a multibillion-dollar initial public offering in New York, is little known to most U.S. investors. But its business is built on a much better known company: ByteDance.

The TikTok parent company accounts for nearly 70% of DayOne’s revenue, according to two people with knowledge of DayOne’s operations. DayOne, which started as a Chinese data center company’s overseas business unit four years ago, has benefitted greatly from ByteDance’s rapid global expansion through TikTok. But that has also left it extraordinarily dependent on a single customer, which the company has acknowledged creates a significant risk for its business.

China is considering new export controls on AI technologies that could potentially restrict the overseas transfers of AI models and chip designs deemed strategically important.

The Ministry of Commerce on Friday issued a draft plan to add 40 technologies across AI, biomedicine and photovoltaic ...