By 10:50pm on Saturday US Eastern Standard Time, the app was not found on Apple and Google's app stores, which are prohibited from offering the platform under a law that required TikTok's China-based parent company, ByteDance, to sell the platform or face a US ban.
"A law banning TikTok has been enacted in the US," a message on the app said.
"Unfortunately, that means you can't use TikTok for now.
"We are fortunate that President Trump has indicated that he will work with us on a solution to reinstate TikTok once he takes office. Please stay tuned," the message said.
Earlier US President-elect Donald Trump said he would "most likely" give TikTok a 90-day reprieve from a potential ban after he takes office, as the app with 170 million American users buzzed with nervous anticipation ahead of the shutdown.
"The 90-day extension is something that will be most likely done, because it's appropriate," Trump told NBC.
"If I decide to do that, I'll probably announce it on Monday."
Users logging on late on Saturday were met with a message that said the law would "force us to make our services temporarily unavailable. We're working to restore our service in the US as soon as possible".
Nearly half of all Americans have the Chinese owned app. (AP PHOTO)
The Chinese-owned app, which has captivated nearly half of all Americans, powered small businesses and shaped online culture, said on Friday it will go dark in the US on Sunday unless President Joe Biden's administration provides assurances to companies such as Apple and Google that they will not face enforcement actions when a ban takes effect.
Under a law passed last year and upheld on Friday by a unanimous Supreme Court, the platform has until Sunday to cut ties with its China-based parent ByteDance or shut down its US operation to resolve concerns it poses a threat to national security.
The White House reiterated on Saturday that it was up to the incoming administration to take action, increasing the likelihood of a shutdown on Sunday.
"We see no reason for TikTok or other companies to take actions in the next few days before the Trump administration takes office on Monday," press secretary Karine Jean-Pierre said.
TikTok did not respond to a request for comment.
The Chinese embassy in Washington on Friday accused the US of using unfair state power to suppress TikTok.Â
"China will take all necessary measures to resolutely safeguard its legitimate rights and interests," a spokesperson said.
A US Supreme Court ruled the platform has until Sunday to cut ties with ByteDance or shut down. (AP PHOTO)
In the lead up, TikTok and its aficionados geared up for goodbye.
Some on the app filmed themselves frantically scrolling or sharing final secrets with their followers ahead of the ban.
Leaders at Oracle, the main cloud computing provider for TikTok's US operations, told staff to prepare to shut down servers that host US TikTok data as soon as 9pm ET on Saturday (1pm AEDT on Sunday) in advance of ban from Sunday, The Information reported.
Without a decision by Biden to formally invoke a 90-day delay in the deadline, companies providing services to TikTok or hosting the app could face enormous financial liability.
Experts said Trump could also direct his Justice Department to "deprioritise" or not enforce the law but it is not clear if that will provide enough legal protection to app store owners Apple and Google providing crucial services for TikTok.
Trump tried to ban and force the divestment of TikTok in 2020 but was blocked by US courts.
Uncertainty over the app's future had sent users - mostly younger people - scrambling to alternatives including China-based RedNote. Rivals Meta and Snap had also seen their shares rise this month ahead of the ban, as investors bet on an influx of users and advertising dollars.
Marketing firms reliant on TikTok have rushed to prepare contingency plans this week in what one executive described as a "hair on fire" moment after months of conventional wisdom saying that a solution would materialise to keep the app running.
There have been signs TikTok could make a comeback under Trump, who has said he wants to pursue a "political resolution" of the issue and last month urged the Supreme Court to pause implementation of the ban.
US search engine startup Perplexity AI submitted a bid on Saturday to ByteDance for Perplexity to merge with TikTok US, a source familiar with the company's plans told Reuters. Perplexity would merge with TikTok US and create a new entity by combining the merged company with other partners, the person added.
Privately held ByteDance is about 60 per cent owned by institutional investors such as BlackRock and General Atlantic, while its founders and employees own 20 per cent each.
with AP
