"It is imperative for the international community to strengthen confidence, act with unity and work together in a collective response," Xi addressed the summit via video link in Beijing.
Calling major infectious disease the enemy of all, Xi said the international community must comprehensively step up international cooperation and foster greater synergy so that humanity as one could win the battle against the COVID-19.
The summit came as the global death toll from the COVID-19, an illness caused by novel coronavirus, has climbed over 21,000 and the number of infections has surpassed 480,000 as of Thursday, according to a count by Johns Hopkins University.
This is the first time for the leaders of the world's 20 major economies to hold a summit online since the mechanism, which used to only gather finance ministers and central bankers, was elevated to be the world's premier platform for international economic cooperation in 2008.
Stressing the outbreak is spreading worldwide and the situation is disturbing and unsettling, Xi called on countries to move swiftly to stem the spread of the virus.
He proposed that a G20 health ministers' meeting be convened as quick as possible to improve information sharing, strengthen cooperation on drugs, vaccines and epidemic control, and cut off cross-border infections.
Xi also proposed a G20 COVID-19 assistance initiative for better information sharing and policy and action coordination with the support of the World Health Organization (WHO).
Guided by the vision of building a community with a shared future for mankind, China will be more than ready to share its good practices and provide assistance in its capacity to countries hit by the growing outbreak, he said.
The summit was chaired by Saudi Arabia's King Salman bin Abdulaziz Al Saud. The kingdom, which holds the presidency of the G20 this year, said it organized the extraordinary meeting to advance global efforts to tackle the pandemic and its economic implications.
The leaders of G20 members were joined by their counterparts from some invited countries, including Spain, Jordan, Singapore and Switzerland, as well as the United Nations, the World Bank and other international organizations, and the chairing states of some regional organizations.
COLLECTIVE RESPONSE
During his address, Xi called on countries to make a collective response for control and treatment at the international level.
China has set up its online COVID-19 knowledge center that is open to all countries, said Xi.
He said it is imperative that countries pool their strengths and speed up research and development of drugs, vaccines and testing capabilities in the hope to achieve early breakthrough to the benefit of all.
China supports WHO in leading the global efforts to develop science-based and proper control and treatment and minimize cross-border spread, said Xi, calling on G20 members to enhance anti-epidemic information sharing with the support of WHO and to promote control and treatment protocols that are comprehensive, systematic and effective.
He called for a high-level meeting on international public health security to be convened in due course.
Leaders of other participating countries and organizations agreed that the fast-spreading outbreak not only severely threatened international public health security, but also cast a huge shadow over world economy, finance and politics.
Facing the common crisis for humanity, no country can keep itself away from the spread of the virus, leaders said, calling for solidarity and more swift and concerted efforts than ever.
"The summit has released a strong signal of unity and coordination among the G20 members," Vice Foreign Minister Ma Zhaoxu said Thursday night, adding that all sides voiced commitment to enhancing cooperation to jointly tackle the crisis.
The agreement made by G20 leaders to share information in a timely manner, guarantee medical supplies and provide assistance to developing countries, especially the least developing countries, explore joint prevention and control measures has rallied global efforts to fight the pandemic, Ma said.
MACRO-ECONOMIC POLICY COORDINATION
The outbreak has disrupted production and demand across the globe and forced hundreds of millions of people around the world into home isolation.
Countries need to leverage and coordinate their macro policies to counteract the negative impact and prevent the world economy from falling into recession, said Xi.
He urged countries to implement strong and effective fiscal and monetary policies, better coordinate financial regulation and jointly keep the global industrial and supply chains stable.
"What China will do in this regard is to increase its supply of active pharmaceutical ingredients, daily necessities, and anti-epidemic and other supplies to the international market," said Xi, adding that China will continue to advance reform and opening-up and contribute to a stable world economy.
Xi called on all G20 members to restore confidence for global economic recovery by cutting tariffs, removing barriers, and facilitating the unfettered flow of trade.
Comprising 19 countries plus the European Union, the G20 members account for about two thirds of the entire human population and some 86 percent of the gross world product.
Leaders agreed to take effective fiscal and monetary policies, ensure global industrial and supply chains stable and strive to reduce the damages caused by the pandemic on world economy.
Ruan Zongze, executive vice president at the China Institute of International Studies, said Xi's remarks at the summit has infused confidence in the international community as the situation in China is moving steadily in a positive direction after a strenuous struggle with targeted measures.
On the other side, China's promise to provide countries with urgently-needed medical supplies, impose no limitation on export and safeguard the stability of industrial and supply chains will also inject vitality into the world economy, said Ruan.