The military organisation has reverse its policy on the entertainment app - which is owned by Beijing-based ByteDance - following guidance from the Pentagon over cybersecurity concerns, despite recently using the popular platform as a recruiting tool.
A spokesperson told CNET: "The Army is following [Office of the Secretary of Defence] guidance on this.
"There was a Cyber Awareness Message sent out on 16 December that identifies TikTok as having potential security risks associated with its use.
"The message directs appropriate action for employees to take in order to safeguard their personal information.
"The guidance is to be wary of applications you download, monitor your phones for unusual and unsolicited texts etc. and delete them immediately and uninstall TikTok to circumvent any exposure of personal information."
Although the military can't ban personnel from using the app on their own personal phones, they have been advised to use caution if they receive any unfamiliar correspondence.