No details were given on specific projects, although Xi said China was planning initiatives in eight areas, including providing US$147 million in emergency food aid, sending 500 agricultural experts to Africa, and providing scholarships, vocational training and trade promotion opportunities.
During a speech at the summit South African President Cyril Ramaphosa delivered a stinging rebuttal to criticism of China's development aid in Africa. Ramaphosa said the meeting "refutes the view that a new colonialism is taking hold in Africa, as our detractors would have us believe".
Xi also promoted Beijing's initiative to build ports and other infrastructure as a tool for "common prosperity" in a world facing challenges from trade protectionism.
Addressing businesspeople prior to the formal opening of the Forum on China-Africa Cooperation, Xi said the "Belt and Road" initiative will expand markets. He tried to mollify concern that Beijing wants to build strategic influence, promising Chinese investment comes with "no political strings attached."
"Unilateralism and protectionism are on the rise. Economic growth lacks robust drive," Xi said in a speech. "China-Africa cooperation under the BRI is a way to common prosperity that brings benefits to both our peoples."
African and other Asian leaders have welcomed "Belt and Road" but some projects have prompted complaints about debt and other problems.
The initiative involves hundreds of projects, most of them built by Chinese contractors and financed by loans from Chinese state-owned banks, across an arc of 65 countries from the South Pacific through Asia to Africa and the Middle East.
In a major blow to China's ambitions, Malaysia recently cancelled Chinese-financed projects worth more than US$20 billion, saying they were unnecessary and would create an unsustainable debt burden. Deeply indebted Pakistan is also reportedly reconsidering some projects in the multi-billion dollar China-Pakistan Economic Corridor that is a key link in the BRI.
The Beijing forum brings together leaders from China and more than 50 African countries. Dozens of African leaders met Xi ahead of the conference.
Xi made no mention of the political and debt concerns that overshadow some BRI projects. But Chinese officials previously have rejected accusations that projects leave host countries too deeply indebted to Chinese lenders.
"China's investment in Africa comes with no political strings attached," Xi said. "China does not interfere in Africa's internal affairs and does not impose its own will on Africa."