May 1 – COVID-19 pandemic: The total number of recovered COVID-19 patients reaches 1 million worldwide, according to data from The Johns Hopkins University.
    May 3–4 – Venezuelan dissidents and an American-based private military company, Silvercorp USA, unsuccessfully attempt to infiltrate Venezuela and forcibly remove President Nicolás Maduro from office.
    May 4 – A team of British and Kenyan scientists announce the discovery of Microsporidia MB, a parasitic microbe in the Microsporidia fungi group that blocks mosquitos from carrying malaria, potentially paving the way for the control of malaria.
    May 5
        COVID-19 pandemic: The U.K. death toll from COVID-19 becomes the highest in Europe at 32,313 after exceeding the death toll of 29,029 in Italy.
        The Philippines' National Telecommunications Commission issues a cease and desist order to the broadcasting operations of ABS-CBN, the country's largest media network, as Congress fails to renew its franchise granted on March 30, 1995. The last time the network was shut down was upon the declaration of martial law by the Philippine dictator Ferdinand Marcos in 1972. On July 10, Members of the Philippine House Committee on Legislative Franchises vote against the franchise renewal of the said network.
    May 6
        Astronomers announce the discovery of the first black hole located in a star system visible to the naked eye.
        COVID-19 pandemic: New evidence indicates that an Algerian-born French fishmonger, who had not traveled to China and did not have contact with any Chinese nationals, was treated for pneumonia from an unknown source on December 27, 2019, now identified as COVID-19.
    May 7 – Eleven people die and over 5,000 fall ill from a styrene gas leak from an LG Polymers chemical plant in Visakhapatnam in Andhra Pradesh, India.
    May 9 – Several Chinese and Indian soldiers are injured in a cross-border clash at the Nathu La crossing. About 150 troops participated in the face-off, which involved fistfights and stone-throwing.
    May 10
        The Iranian Navy frigate Jamaran accidentally strikes the Iranian support vessel Konarak with a missile, killing nineteen sailors. This is the first friendly fire incident since February 2019, when an Indian Mil Mi-17 helicopter was mistakenly shot down by Indian air defense forces.
        COVID-19 pandemic:
            The number of confirmed cases of COVID-19 passes 4 million worldwide.
            Wuhan reports its first coronavirus cases in more than a month. An 89-year-old man is confirmed positive, but his wife and several members of the community are recorded as asymptomatic cases.
    May 11 – The Max Planck Institute for Evolutionary Anthropology publishes the result of radiocarbon and DNA analysis from the fossils that has been found in the Bacho Kiro cave, Bulgaria. The result, showing that the fossils belong to Homo sapiens instead of Neanderthal, indicates that modern humans may have arrived in Europe thousands of years earlier than previously thought.
    May 12 – Gunmen storm a maternity hospital and kill 24 people, including two newborn babies, in Dashte Barchi, a majority-Shia neighborhood of Kabul, Afghanistan. In a separate incident in Kuz Kunar, 32 people are killed at a funeral by a suicide bomber.
    May 14
        COVID-19 pandemic:
            The global death toll from COVID-19 exceeds 300,000.
            The UN warns of a global mental health crisis caused by isolation, fear, uncertainty and economic turmoil.
        NATO Secretary General Jens Stoltenberg says the military alliance is "ready to support" the UN-recognized Government of National Accord while Greece, a member state of NATO, strongly criticizes Stoltenberg's remarks, saying his recognition of the "Muslim Brotherhood government" does not reflect the positions of the military alliance.
    May 15 – Researchers announce a 2.5 cm millipede fossil belonging to the Kampecaris genus, discovered on the island of Kerrera in the Scottish Inner Hebrides, is the world's oldest-known land animal, which lived 425 million years ago in the Silurian period.
    May 16
        COVID-19 pandemic: Bundesliga becomes the first major sports league to resume its season since March 11.
        Félicien Kabuga, a Rwandan businessman responsible for supporting the Rwandan genocide, is arrested in Asnières-sur-Seine, France, after 26 years as a fugitive.
    May 18
        The United Nations Office for the Coordination of Humanitarian Affairs announces that nearly 1 million people are affected and at least 24 people have died in flash floods that have hit Beledweyne and Jowhar, Somalia.
        In a historic move, the World Health Organization holds its annual World Health Assembly using video conferencing instead of in-person meetings.
    May 19 – Palestinian President Mahmoud Abbas announces the termination of all agreements, including security ones, with Israel and the United States in response to Israel's plans to annex the Jordan Valley.
    May 21
        Cyclone Amphan makes landfall in eastern India and Bangladesh, killing over 100 people and forcing the evacuation of more than 4 million others. It causes over US$13 billion in damage, making it the costliest cyclone ever recorded in the North Indian Ocean, shattering the record previously held by Nargis.
        The U.S. announces it will withdraw from the Open Skies Treaty within six months, alleging continuous violations by Russia.
        COVID-19 pandemic: The number of confirmed cases of COVID-19 passes 5 million worldwide, with 106,000 new cases recorded over the past 24 hours, the highest single-day figure so far.
    May 22
        Flight PK8303, a Pakistan International Airlines passenger aircraft, crashes in a residential area near Karachi, in Pakistan, killing 97 of the 99 total people on board and injuring dozens on the ground.
        COVID-19 pandemic: Brazil overtakes Russia to become the country with the second highest number of COVID-19 cases, with over 330,000 reported. President Jair Bolsonaro continues to dismiss the threat of the virus.
    May 23 – COVID-19 pandemic: China reports no new cases for the first time since the pandemic began, according to the National Health Commission.
    May 24
        Mining corporation Rio Tinto admits to blowing up the 46,000-year-old Juukan Gorge caves in the Pilbara area of Western Australia. The firm later issues an apology to the two Aboriginal peoples who are the traditional owners of the site.
        A "once in a decade" storm batters 3,000 kilometres (1,900 mi) of the coast of Western Australia.
        Egyptian President Abdel Fattah el-Sisi pardons 3,157 prisoners to celebrate Eid al-Fitr and, two days later, President of Zambia Edgar Lungu pardons nearly 3,000 inmates to commemorate Africa Freedom Day.
    May 26
        Protests caused by the killing of George Floyd break out across hundreds of cities in the U.S. and around the world. These are followed by further protests and rallies on June 6 against racism and police brutality around the world.
        Costa Rica becomes the first Central American country to legalise same-sex marriage.
        LATAM Airlines, the largest air carrier in Latin America, files for Chapter 11 bankruptcy.
    May 27
        The Chinese National People's Congress votes in favour of national security legislation that criminalizes "secession", "subversion", "terrorism" and foreign interference in Hong Kong; the legislation grants sweeping powers to the Chinese central government to suppress the Hong Kong democracy movement, including banning activist groups and curtailing civil liberties. The U.S. government responds by declaring Hong Kong is "no longer autonomous" under the United States-Hong Kong Policy Act.
        COVID-19 pandemic: The U.S. death toll passes 100,000 – more Americans than were killed in the Vietnam War and Korean War combined, and approaching that of the First World War, where 116,000 Americans died in combat. The total number of cases continues to rise, although the rate is slowing.
    May 28 – A court in Rwanda sentences former Mayor of Nyakizu Ladislas Ntaganzwa to life imprisonment for his role in orchestrating the massacre of hundreds of thousands of people in the Rwandan genocide.
    May 30 – The first crewed flight of the SpaceX Dragon 2 (initially scheduled for May 27 but delayed due to weather) is launched from Cape Canaveral, Florida, the first manned spacecraft to take off from U.S. soil since the retirement of the Space Shuttle in 2011.
    May 31 – COVID-19 pandemic: The number of confirmed cases of COVID-19 passes 6 million worldwide.

India

    May 5 – Skirmishes began between India and China. Several Indian and Chinese soldiers are injured in a cross-border clash at the Nathu La crossing. About one hundred and fifty soldiers were involved in the face-off which included fistfights and stone-throwing.
    May 6 – Wanted terrorist Riyaz Naikoo of the terror group Hizb-ul-Mujahideen, killed in a gun battle with Indian security forces.
    May 7 – 13 people were killed from a gas leak at a chemical plant in Visakhapatnam, Andhra Pradesh.
    May 20 – Cyclone Amphan hit the eastern part of India and lead to flood like situation in many South-eastern states.
    May 27 – A petroleum gas and oil leak occurred in Indian Oil's Baghjan Oilfield, in Assam.