Chinese President Xi Jinping is "trying to exploit Trump's weaknesses," Soros told the gathering. He also accused Xi of using "artificial intelligence to have total control of his people."
And while Soros did not discuss the Democratic presidential primary, in which he has yet to make an endorsement, he said the 2020 election will not just determine the relationship between Trump and Xi, but the "fate of the world."
Soros, the 89-year-old Democratic megadonor who has a net worth of just over $8 billion, made his comments at a private annual dinner set amid a conference known for featuring elite business and political leaders.
Soros' fresh criticism of Trump and the Chinese government under Xi came after the two nations agreed to a so-called phase one trade deal. The agreement calls for China to increase its purchases of U.S. manufacturing, energy and agricultural goods and services by at least $200 billion over two years and includes provisions to root out intellectual property theft and forced technology transfers.
While Trump has said negotiations on a phase two agreement will begin soon, many business executives at the WEF have raised doubts that another agreement will be made over the next year.
He also leveled direct attacks at Trump, saying the president "is a con man and a narcissist, who wants the world to revolve around him."
"When his fantasy of becoming president became a reality," that narcissism dialed up, Soros said. "This has turned his narcissism into a malignant disease."
The White House did not immediately respond to CNBC's request for comment.
Soros did acknowledge Trump's ability to retain support among his political base and undermine Democratic criticism especially in light of his ongoing impeachment trial in the Senate.
"He has an instinct of how they are going to respond to his actions," Soros said. "This makes the tasks of the Democrats who impeached him extremely difficult."
"The trial in the Senate is setting up to be strictly pro forma," he added, noting that Republicans appear to be in lockstep with the president and unlikely to vote to remove him from office.
At last year's conference, Soros labeled Xi as the "most dangerous" opponent to those who believe in open society. During that same dinner, Soros took aim at Trump's negotiating tactics with China in the buildup to the eventual trade deal that was signed last week.
"Regrettably, President Trump seems to be following a different course: Make concessions to China and declare victory while renewing his attacks on U.S. allies. This is liable to undermine the U.S. policy objective of curbing China's abuses and excesses," he said at the time.
Although Soros avoided discussing the Democratic primary at the dinner, he has continued to use his wealth to back a slew of political causes outside of the presidential election.
His new super PAC, the Democracy PAC, was involved with funding several Democratic candidates during the recent Virginia state elections. Democrats went on to take control of the Virginia Legislature for the first time in more than two decades.
Records show that the PAC has raised just over $5 million and has that amount on hand.
Soros has been one of the top Democratic donors. During the 2016 presidential election, he spent more than $20 million on Democrats, including at least $8 million on a pro-Hillary Clinton super PAC, Priorities USA Action, according to the nonpartisan Center for Responsive Politics.
Soros is ranked second among all political donors in the 2020 election cycle, with over $6 million in contributions. Just ahead of him is billionaire and presidential candidate Tom Steyer, who has contributed just more than $23 million.
While Soros has not endorsed a candidate, he said in October that Sen. Elizabeth Warren, a populist from Massachusetts, is "the most qualified to be president."
— CNBC's Thomas Franck reported from Englewood Cliffs, New Jersey.