TikTok said it is "in the process of restoring its service" in the US, adding it will work with President-elect Donald Trump on a long-term solution that keeps the social media app in the United States.
TikTok, which is owned by Chinese firm ByteDance, stopped working for its 170 million American users after a law took effect banning the app's continued operation over concerns that Americans' data could be misused by Chinese officials.
In a post on X, TikTok thanked Mr Trump for "providing the necessary clarity and assurance to our service providers that they will face no penalties providing TikTok" to users in the US.
"It's a strong stand for the First Amendment and against arbitrary censorship," it said.
Before TikTok's statement, Mr Trump had said he will issue an executive order when he takes office tomorrow that would let TikTok be operational, while adding he would like the US to have a 50% ownership position in a joint venture.
"I would like the United States to have a 50% ownership position in a joint venture," Mr Trump said on social media.
The developments come after Mr Trump's incoming national security adviser Mike Waltz told CNN that the Republican has not ruled out continued Chinese ownership of TikTok coupled with "firewalls to make sure that the data is protected" on US soil.
Mr Waltz said Mr Trump is working to "save TikTok", adding an extension is needed to evaluate deals on the table in relation to the app.
Every company in China has some connection to the Chinese Communist Party, he said.
TikTok told users attempting to use the app in the US: "A law banning TikTok has been enacted in the US. 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."
Other apps owned by ByteDance, including video editing app Capcut and lifestyle social app Lemon8, were also offline and unavailable in US app stores.
TikTok users logging on 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".
It was not clear if any US users could still access the app, but it was no longer working for many users and people seeking to access it through a web application were met with the same message that TikTok was no longer working.
The Chinese-owned app, which has captivated nearly half of all Americans, powered small businesses and shaped online culture, said earlier this week it will go dark in the US unless President Joe Biden's administration provided assurance 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 had until today 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 that it was up to the incoming administration to take action.
"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 in a statement.
TikTok did not respond to a request for comment on the new White House statement.
The Chinese embassy in Washington accused the US of using unfair state power to suppress TikTok.
"China will take all necessary measures to resolutely safeguard its legitimate rights and interests," a spokesperson said.
