The visit, planned for weeks, comes as Beijing faces 145 per cent US duties, while Vietnam is negotiating a reduction of threatened US tariffs of 46 per cent that would otherwise apply in July after a global moratorium expires.
"The two sides should strengthen co-operation in production and supply chains," Xi said in an article in Nhandan, the newspaper of Vietnam's Communist Party, posted ahead of his arrival on Monday.
He also urged more trade and stronger ties with Hanoi on artificial intelligence and the green economy.
"There are no winners in trade wars and tariff wars, and protectionism has no way out," Xi said, without mentioning the US specifically.
"We must firmly safeguard the multilateral trading system, maintain the stability of the global industrial and supply chains, and maintain the international environment for open co-operation," he said.
Under pressure from Washington, Vietnam is tightening controls on some trade with China to make sure goods exported to the United States with a "Made in Vietnam" label have sufficient added value in the country to justify that.
Vietnam is a major industrial and assembly hub in Southeast Asia. Most of its imports are from China while the United States is its main export market. The country is a crucial source of electronics, shoes and apparel for the United States.
Xi will visit Vietnam from April 14 to 15, and Malaysia and Cambodia from April 15 to 18. He last visited Cambodia and Malaysia nine and 12 years ago, respectively.
Xi's trip to Hanoi, his second in less than 18 months, aims to consolidate relations with a strategic neighbour that has received billions of dollars of Chinese investments in recent years as China-based manufacturers moved south to avoid tariffs imposed by the first Trump administration.
The two Communist-run countries are set to sign about 40 agreements in multiple sectors, Vietnam's Deputy Prime Minister Bui Thanh Son said on Saturday.
Despite strong economic ties, tensions frequently surface between the countries over contested boundaries in the South China Sea.
Vietnam's concessions to the US to avoid tariffs may also irritate Beijing, as they include the deployment of Elon Musk's Starlink satellite communication service in the Southeast Asian nation, in addition to the crackdown on some trade with China over possible fraud on rules of origin.
The two other countries on Xi's Southeast Asia itinerary, Cambodia and Malaysia, are facing US duties of 49 per cent and 24 per cent, respectively, and have already begun reaching out to the US to seek a reprieve.
