- May 1 – May Day (Europe)
- May 1 – Labour Day (India)
- May 1 – Maharashtra State Day (India)
- May 1 – Labour Day (Guyana)
- May 1 – Labour Day (Brazil)
- May 2 – Dos de Mayo (Spain)
- May 5 – Liberation Day (Ethiopia, Netherlands, Denmark)
- May 5 – Children's Day (Japan, South Korea)
- May 5 – Cinco de Mayo (Mexico)
- May 5 – Indian Arrival Day Guyana
- May 6 – Lag Ba'omer (Judaism)
- May 6 – St George's Day (Bulgaria)
- May 8 – Victory in Europe Day
- May 9 – Europe Day (European Union)
- May 16 – Jerusalem Day (Israel)
- May 17 – Constitution Day (Norway)
- May 24 – Victoria Day (Canada)
- May 24 – Saints Cyril and Methodius Day (Bulgaria, Republic of Macedonia)
- May 25 – African Liberation Day
- May 26 – National Sorry Day (Australia)
- May 26 – Independence Day (Guyana)
- May 27 – Children's Day (Nigeria)
- May 28 – Memorial Day (United States)
- May 28 – Republic Day (Armenia, Azerbaijan)
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- May 28 – Spring Bank Holiday (United Kingdom)
- May 28 – Whit Monday (France, Germany, Austria, Switzerland, Luxembourg, Greece, Hungary, Belgium, The Netherlands)
- May 29 – Ratu Sir Lala Sukuna Day (Fiji)
- Mother's Day
- May 8 (Parent's Day) – South Korea and Albania
- May 10 – Mexico
- May 10 – South America, El Salvador, Guatemala, Oman, and Pakistan
- May 13 (2nd Sunday) – Anguilla, Aruba, Australia, Austria, Bahamas, Barbados, Bangladesh, Belgium, Belize, Bermuda, Bonaire, Brazil, Brunei, Canada, Chile, Colombia, Cuba, Croatia, Curaçao, Czech Republic, Denmark, Ecuador, Estonia, Finland, Germany, Greece, Grenada, Honduras, Hong Kong, Iceland, India, Italy, Jamaica, Japan, Latvia, Malta, Malaysia, The Netherlands, New Zealand, Peru, Philippines, Puerto Rico, Singapore, Slovakia, South Africa, Suriname, Switzerland, Taiwan, Trinidad and Tobago, Turkey, United States, Uruguay, Venezuela, Zimbabwe
- May 26 – Poland
- May 27-Bolivia
- May 27 (last Sunday) – France (switches to first Sunday of June if coincides with Pentecost), Dominican Republic, Haiti, Sweden, and Morocco
- May 30 – Nicaragua
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