TikTok won't face the most drastic sanctions until after the Nov. 3 election, but WeChat users could feel the effects as early as Sunday.
The order, which cited national security and data privacy concerns, follows weeks of dealmaking over the video-sharing service TikTok.
Trump had said this week that he does not like the idea of ByteDance keeping majority control of TikTok.
The administration, however, has provided no specific evidence that TikTok has made U.S. users’ data available to the Chinese government.
Some cybersecurity experts question whether the administration's efforts are more political than rooted in legitimate concerns about Chinese threats to data security.