Donald Trump has told President Xi Jinping that America will honour Washington's "one China" policy, which has been at the centre of friction between the global powers since his election as US president.
During a phone call on Thursday night Mr Trump "agreed, at the request of President Xi", to honour the policy that requires Washington to maintain only unofficial ties with China's rival Taiwan, the White House said.
The White House described the call as "extremely cordial" and said the two leaders had invited each other to visit.
Before taking office, Mr Trump questioned the policy, which shifted diplomatic recognition from self-governing Taiwan to China in 1979, and said it was open to negotiation.
China has bristled at the "one China" comments by Mr Trump, who wants to pressure Beijing to narrow its huge trade surplus with America.
Mr Trump had accused Beijing of unfair trade practices, criticised China's military build-up in the South China Sea and accused China of doing too little to pressure North Korea.
Some had questioned why Mr Trump had taken so long to call Mr Xi given that he had already spoken with more than a dozen world leaders.
Chinese observers also noted that Mr Trump had broken with his predecessors in not extending good wishes to the Chinese people on the occasion of last month's Lunar New Year holiday, before issuing of a belated greeting on Wednesday.
China claims Taiwan as its own territory and complained after Mr Trump upset decades of diplomatic precedent by talking by phone with Taiwanese president Tsai Ing-wen shortly after winning November's presidential election.
In December, Mr Trump said in an interview that he did not feel "bound" by the decades-old China policy unless the US could gain concessions in trade and other areas.
Washington has robust unofficial relations with Taiwan and provides it with arms to guard against Beijing's threat to use force to reunify.
Underscoring uncertainty in the relationship, the call between the leaders came as the US Pacific Command reported a Chinese jet and a US Navy patrol plane had an "unsafe" encounter over the South China Sea this week.
Pacific Command spokesman Robert Shuford said on Friday that the "interaction" between a Chinese KJ-200 early warning aircraft and a US Navy P-3C plane took place on Wednesday in international airspace.
He did not say what was unsafe about the encounter but said the US plane was on a routine mission and operating according to international law.
China routinely complains about US military surveillance missions close to its southern island province of Hainan, which is home to numerous sensitive military installations.
A collision between a US EP-3 surveillance plane and a Chinese naval air force jet in April 2001 resulted in the death of the Chinese pilot and the 10-day detention of the US air crew by China.