Trump's face-to-face talks with Xi in the South Korean city of Busan, their first since 2019, marked the finale of a whirlwind Asia trip on which he also touted trade breakthroughs with South Korea, Japan and Southeast Asian nations.
"It was an amazing meeting," Trump told reporters aboard Air Force One on Thursday shortly after he left Busan, ranking the talks a "12 out of 10".
Trump said tariffs on Chinese imports would be cut to 47 per cent from 57 per cent by halving the rate of tariffs related to trade in fentanyl precursor drugs to 10 per cent.
Xi will work "very hard to stop the flow" of fentanyl, a deadly synthetic opioid that is the leading cause of American overdose deaths, Trump said.
The tariff was reduced "because I believe they are really taking strong action".
China agreed to pause export controls announced in October on rare earths, elements that play vital roles in cars, planes and weapons that have become Beijing's most potent source of leverage in its trade war with the United States.
The pause would last for a year, China's commerce ministry said, adding the two sides had also reached consensus on fentanyl co-operation and expanding agricultural trade.
The reaction to the detente in global stock markets was muted, with major Asian indices and European futures swinging between gains and losses.
Among major US trading partners, only Brazil and India are still subject to higher tariffs.
In the run-up to the meeting, world stock markets from Wall Street to Tokyo had hit records on hopes of a breakthrough in a trade war between the world's two largest economies that has disrupted supply chains and rocked global business confidence.
The cordial meeting on the sidelines of the Asia-Pacific Economic Co-operation summit ran for more than one-and-a-half hours.
Trump repeatedly talked up prospects of reaching agreement with Xi since US negotiators on Sunday said they had agreed a framework with China to avoid 100 per cent US tariffs on its goods and defer China's export curbs on rare earths, a sector it dominates.
It was normal for the superpowers to have frictions now and then, Xi told Trump via a translator, as the talks began at a South Korean air base.
"China's development and rejuvenation are not incompatible with President Trump's goal of 'Making America Great Again," Xi said.
Besides trimming the fentanyl tariffs, Beijing had sought an easing of export controls on sensitive US technology, and a roll-back of new US port fees on Chinese vessels designed to combat China's global dominance in shipbuilding, ocean freight and logistics.
Trump made no immediate comment on US concessions but said China would buy "tremendous amounts" of US soybeans and other farm products "starting immediately".
Before the summit, China bought its first cargoes of US soybeans in several months, Reuters reported exclusively on Wednesday.
The White House has signalled it hopes the summit will be the first of several between the leaders in the coming year.
Trump said he would travel to China in April before he receives Xi in the United States.
Trump said he did not discuss Nvidia's state-of-art Blackwell AI chip with Xi, despite a suggestion the previous day that he could do so.
In August, Reuters reported that Nvidia was working on a downgraded version of the Blackwell to sell to China.
