The rapid globalization of money, goods, services, taxation, knowledge, people, political ideas, digitalization, and especially pathogens and ecological pollutants has intensified, along with rising inequality, multipolarity, protectionism, isolationism and geopolitical tensions. Together these factors present new challenges to 21st century global governance led by the systemically significant states which make up the Group of Twenty (G20). G20 governance has expanded in response, but with more success on its old, incompletely globalized economic agenda than on its newer, more globalized digitalization, health pandemics and climate change agendas. The most recent G20 summit in Osaka, Japan on 28–29 June 2019 did make advances on tax and digitalization but not on the looming health risks and the existential threat of climate change. Preparations for the Saudi Arabian-hosted Riyadh summit, to be held on 21–22 November 2020, have made some progress on the latter amidst the unprecedented crisis posed by the COVID-19 pandemic. The crisis shows that the G20’s architecture needs to be further strengthened by institutionalizing G20 environment and health ministers’ meetings; inviting the executive heads of the United Nations (UN) bodies for climate change, biodiversity, the environment and health, as well as the leaders of key outside countries, to the summits; giving the UN and World Health Organization the same G20 status as the International Monetary Fund and World Bank; and holding a second annual summit at the UN each September focused on the sustainable development goals.