Trump signed an executive order pushing back Thursday's deadline for 90 more days, a step that he had previously signaled.
The Republican president had already twice granted a reprieve from federal enforcement of a law that mandated the sale or shutdown of TikTok that was supposed to take effect in January, absent significant progress toward a sale.
Trump has said he wants to keep the app, which helped him woo young voters in the 2024 presidential election, active in the US.
He has also expressed optimism that Chinese President Xi Jinping would approve a deal that preserves the app, though it's not clear how significantly the topic has featured in the two countries' ongoing trade talks to resolve a tariff dispute.
"We are grateful for President Trump's leadership and support in ensuring that TikTok continues to be available," TikTok said in a statement posted on its website.
The company said it is continuing to work with US Vice President JD Vance's office on the matter.
"President Trump will sign an additional executive order this week to keep TikTok up and running," White House press secretary Karoline Leavitt said on Tuesday.
"President Trump does not want TikTok to go dark," she added, saying the administration will spend the next three months making sure the sale closes so that Americans can keep using TikTok with the assurance that their data is safe and secure.
Trump had said on Tuesday that he would "probably, yeah," extend the deadline.
"Probably have to get China approval but I think we'll get it," he told reporters aboard Air Force One.
"I think President Xi will ultimately approve it."
A 2024 law required TikTok to stop operating by January 19 unless TikTok's Chinese parent ByteDance had completed divesting the app's US assets or demonstrated significant progress toward a sale.
Trump began his second term as president on January 20 and opted not to enforce the law. He first extended the deadline to early April, and then again last month to June 19.
In March, Trump said he would be willing to reduce tariffs on China to get a deal done with ByteDance to sell the short-video app used by 170 million Americans.
A deal had been in the works this spring that would spin off TikTok's US operations into a new US-based firm, majority-owned and operated by US investors, but it was put on hold after China indicated it would not approve it following Trump's announcements of steep tariffs on Chinese goods.
Some Democrats argue that Trump has no legal authority to extend the deadline and suggest that the deal under consideration would not meet legal requirements.
