The app had faced being blocked from Apple's App Store and Android's Google Play marketplace from 23:59 Eastern time.
Existing US-based users would have been able to continue using it.
But they would not have been able to re-download the app if they deleted it from their phones, nor have been offered software updates.
Judge Carl Nichols of the US District Court for the District of Columbia issued a temporary injunction on Sunday evening at the request of TikTok.
The opinion was sealed, meaning that no reason for the decision was released.
TikTok had argued that forcing it off the iOS and Android app stores would have violated the First and Fifth Amendments of the US constitution.
It claimed that preventing some users joining the app unlawfully impinged upon their freedom of speech and that the firm's own right to due process would have been breached by not giving it a proper opportunity to defend itself first.
"How does it make sense to impose this app store ban tonight when there are negotiations underway that might make it unnecessary?" added a member of the app's legal team.
The US government's lawyers in turn had described the app's parent as being "a mouthpiece" for the Chinese Communist Party (CCP).