| Sat, December 1 | Inauguration day | Mexico | National Holiday |
| Sat, December 1 | Restoration of Independence | Portugal | National Holiday |
| Sat, December 1 | National holiday | Romania | National Holiday |
| Sat, December 1 | Republic Day | Central african republic | Public Holiday |
| Sat, December 1 | Day of the First President of the Republic of Kazakhstan | Kazakhstan | Public Holiday |
| Sat, December 1 | World AIDS Day | – | International |
| Sat, December 1 | Small Business Saturday | United kingdom |
| Sun, December 2 | First Sunday of Advent | Multiple [Show] | Multiple Types |
| Sun, December 2 | First Sunday Advent | Multiple [Show] | Observance |
| Sun, December 2 | Good Neighborliness Day | Turkmenistan | Observance |
| Sun, December 2 | National Day | Laos | Public Holiday |
| Sun, December 2 | International Day for the Abolition of Slavery | – | International |
| Sun, December 2 | National Mutt Day | – | Weird |
| Mon, December 3 | First Day of Hanukkah | Multiple [Show] | Jewish Holiday |
| Mon, December 3 | Chanukah/Hanukkah (first day) | United states | Jewish Holiday |
| Mon, December 3 | Anniversary of the Coronation of King Tupou I | Tonga | Public Holiday |
| Mon, December 3 | Hanukkah I (Holiday of lights) | Israel | Observance, Hebrew |
| Mon, December 3 | Day of Navarre | Spain (Navarre) | Local Holiday |
| Mon, December 3 | Day of the First President of the Republic of Kazakhstan observed | Kazakhstan | Public Holiday |
|
| Mon, December 3 | International Day of Persons with Disabilities | – | International |
| Tue, December 4 | Hanukkah II | Israel | Observance, Hebrew |
| Tue, December 4 | National Cookie Day | – | Weird |
| Wed, December 5 | St Nicholas’ Eve/Sinterklaas | Netherlands | Observance |
| Wed, December 5 | Hanukkah III | Israel | Observance, Hebrew |
| Wed, December 5 | International Volunteer Day for Economic and Social Development | – | International |
| Wed, December 5 | World Soil Day | – | International |
| Thu, December 6 | St. Nicholas Day | – | Christian |
| Thu, December 6 | Independence Day | Finland | National Holiday |
| Thu, December 6 | Saint Nicholas Day | Multiple [Show] | Observance |
| Thu, December 6 | Foundation of Quito | Ecuador | Local Holiday |
| Thu, December 6 | St Nicholas’ Day | Multiple [Show] | Observance |
| Thu, December 6 | Army Day | Ukraine | Observance |
| Thu, December 6 | Hanukkah IV | Israel | Observance, Hebrew |
| Thu, December 6 | Constitution Day | Spain (All Except An , Ar , Ce , Cl , Ex , Lo , M , Ml , Mu , O , Vc) | National Holiday |
| Fri, December 7 | National Heroes Day | East timor | Public Holiday |
| Fri, December 7 | Eve of the Feast of the Immaculate Conception | Colombia | Observance |
| Fri, December 7 | Pearl Harbor Remembrance Day | United states | Observance |
| Fri, December 7 | The Feast of St. Ambrose (Milan) | Italy | Local Holiday |
| Fri, December 7 | Spitak Remembrance Day | Armenia | Observance |
| Fri, December 7 | Hanukkah V | Israel | Observance, Hebrew |
| Fri, December 7 | Western Province Day | Solomon islands | Local Holiday |
| Fri, December 7 | International Civil Aviation Day | – | International |
| Fri, December 7 | Farmer’s Day | Ghana | Public Holiday |
| Sat, December 8 | Bodhi Day | – | Buddhist |
| Sat, December 8 | Mother Day | Panama | National Holiday |
| Sat, December 8 | Immaculate Conception | Multiple [Show] | Multiple Types |
| Sat, December 8 | Feast of the Immaculate Conception | Multiple [Show] | Multiple Types |
| Sat, December 8 | Constitution Day | Multiple [Show] | Multiple Types |
| Sat, December 8 | Day of Our Lady of Immaculate Conception | East timor | Public Holiday |
| Sat, December 8 | Virgin of Caacupé Day | Paraguay | National Holiday |
| Sat, December 8 | Feast of the immaculate Conception | Multiple [Show] | Multiple Types |
| Sat, December 8 | Hanukkah VI/Rosh Chodesh Tevet | Israel | Observance, Hebrew |
| Sat, December 8 | Inmaculate Conception Day | Chile | National Holiday |
| Sat, December 8 | Battle Day | Falkland islands | Public Holiday |
| Sat, December 8 | Saint Kliment Ohridski’s Day | Macedonia, republic of | National Holiday |
| Sat, December 8 | National Youth Day | Albania | National Holiday |
| Sat, December 8 | National Brownie Day | – | Weird |
| Sun, December 9 | Second Sunday Advent | Multiple [Show] | Observance |
| Sun, December 9 | National Heroes Day | Antigua and barbuda | Public Holiday |
| Sun, December 9 | Hanukkah VII | Israel | Observance, Hebrew |
| Sun, December 9 | Republic Day | Tanzania | Public Holiday |
| Sun, December 9 | International Anti-Corruption Day | – | International |
| Mon, December 10 | Last day of Hanukkah | Multiple [Show] | Jewish Holiday |
| Mon, December 10 | International Human Rights Day | Multiple [Show] | Multiple Types |
| Mon, December 10 | Last Day of Chanukah | United states | Jewish Holiday |
| Mon, December 10 | Human Rights Day | Multiple [Show] | International |
| Mon, December 10 | Hanukkah VIII | Israel | Observance, Hebrew |
| Tue, December 11 | Republic Day | Madagascar | Public Holiday |
| Tue, December 11 | Human Rights and Peace Day | Kiribati | Public Holiday |
| Tue, December 11 | International Mountain Day | – | International |
| Tue, December 11 | Anniversary of the Statute of Westminster | Canada | Observance |
| Wed, December 12 | Day of the Virgin of Guadalupe | Mexico | Bank Holiday |
| Wed, December 12 | Feast of Our Lady of Guadalupe | United states | Observance |
| Wed, December 12 | Jamhuri Day | Kenya | Public Holiday |
| Wed, December 12 | Day of Neutrality | Turkmenistan | Public Holiday |
| Thu, December 13 | National Guard Birthday | United states | Observance |
| Thu, December 13 | Republic Day | Malta | National Holiday |
| Thu, December 13 | National Day | Saint lucia | Public Holiday |
| Sat, December 15 | National Cupcake Day | – | Weird |
| Sun, December 16 | Third Sunday Advent | Multiple [Show] | Observance |
| Sun, December 16 | National Day | Bahrain | Public Holiday |
| Sun, December 16 | Independence Day | Kazakhstan | Public Holiday |
| Sun, December 16 | Day of Reconciliation | South africa | Public Holiday |
| Mon, December 17 | Pan American Aviation Day | United states | Observance |
| Mon, December 17 | Wright Brothers Day | United states | Observance |
| Mon, December 17 | National Day (second day) | Bahrain | Public Holiday |
| Mon, December 17 | Independence Day observed | Kazakhstan | Public Holiday |
| Mon, December 17 | Independence Day (Day 2) | Kazakhstan | Public Holiday |
| Mon, December 17 | Day of Reconciliation observed | South africa | Public Holiday |
| Tue, December 18 | National Day | Qatar | Public Holiday |
| Tue, December 18 | Asarah B’Tevet | Israel | Observance, Hebrew |
| Tue, December 18 | Nigerien Republic Day | Niger | Public Holiday |
| Tue, December 18 | International Migrants Day | – | International |
| Tue, December 18 | Arabic Language Day | – | International |
| Wed, December 19 | Remembrance Day for Roma and Sinti killed by Genocide | Germany | Observance |
| Wed, December 19 | St. Nicholas Day | Ukraine | Observance, Orthodox |
| Wed, December 19 | Separation Day | Anguilla | Public Holiday |
| Thu, December 20 | Macau S.A.R. Establishment Day | Macau | Public Holiday |
| Thu, December 20 | Abolition of Slavery | Reunion | Public Holiday |
|
| Thu, December 20 | International Human Solidarity Day | – | International |
| Fri, December 21 | December Solstice | Multiple [Show] | Season |
| Fri, December 21 | Dōngzhì Festival | Taiwan | Observance |
| Fri, December 21 | Turkish Language Day (Turkish community) | Macedonia, republic of | Optional Holiday |
| Fri, December 21 | Yule | – |
| Sat, December 22 | Unity Day | Zimbabwe | Public Holiday |
| Sun, December 23 | Fourth Sunday Advent | Multiple [Show] | Observance |
| Sun, December 23 | Emperor’s Birthday | Japan | National Holiday |
| Mon, December 24 | Christmas Eve | Multiple [Show] | Multiple Types |
| Mon, December 24 | Christmas Eve (Half Day) | Paraguay | National Holiday |
| Mon, December 24 | Christmas Eve (from noon) | Iceland | National Holiday |
| Mon, December 24 | Christmas Eve (from 2pm) | Brazil | Optional Holiday |
| Mon, December 24 | Birth Date of Kim Jong Suk | North korea | Public Holiday |
| Mon, December 24 | Emperor’s Birthday observed | Japan | National Holiday |
| Mon, December 24 | Yap Constitution Day | Micronesia | Local Holiday |
| Mon, December 24 | Independence Day | Libya | Public Holiday |
| Tue, December 25 | Christmas | Multiple [Show] | Multiple Types |
| Tue, December 25 | Christmas Day | Multiple [Show] | Multiple Types |
| Tue, December 25 | Catholic Christmas Day | Belarus | National Holiday |
| Tue, December 25 | Constitution Day | Taiwan | Observance |
| Wed, December 26 | Boxing Day | Multiple [Show] | Multiple Types |
| Wed, December 26 | St. Stephen’s Day | Multiple [Show] | Multiple Types |
| Wed, December 26 | St Stephen’s Day | Multiple [Show] | Multiple Types |
| Wed, December 26 | Second day of Christmas | Multiple [Show] | National Holiday |
| Wed, December 26 | Kwanzaa (until Jan 1) | United states | Observance |
| Wed, December 26 | Day After Christmas Day | United states (Ks , Ky , Nc , Nc , Nh , Sc , Tx) | State Holiday |
| Wed, December 26 | 2nd Christmas Day | Denmark | National Holiday |
| Wed, December 26 | Synaxis of the Mother of God | Greece | Public Holiday |
| Wed, December 26 | Second Day of Christmas | Multiple [Show] | National Holiday |
| Wed, December 26 | Boxing Day (bank holiday) | Malta | Bank Holiday |
| Wed, December 26 | Family Day | Vanuatu | Public Holiday |
| Wed, December 26 | National Day of Thanksgiving | Solomon islands | Public Holiday |
| Wed, December 26 | Independence and Unity Day | Slovenia | National Holiday |
| Wed, December 26 | Day of Goodwill | Multiple [Show] | Public Holiday |
| Thu, December 27 | Constitution Day | North korea | Public Holiday |
| Fri, December 28 | Holy Innocents | – | Christian |
| Fri, December 28 | Incwala Day | Swaziland | Public Holiday |
| Fri, December 28 | Day of the Holy Innocents | Mexico | Observance |
| Fri, December 28 | Republic Day | South sudan | Public Holiday |
| Sat, December 29 | Working day – moved weekend | Russia | Working Day (moved Weekend) |
| Sat, December 29 | Independence Day | Mongolia | Public Holiday |
| Sun, December 30 | Rizal Day | Philippines | Regular Holiday |
| Sun, December 30 | Day of the Declaration of Slovakia as an Independent Ecclesiastic Province | Slovakia | Observance |
| Sun, December 30 | National Bacon Day | – | Weird |
| Mon, December 31 | Watch Night | – | Christian |
| Mon, December 31 | New Year’s Eve | Multiple [Show] | Multiple Types |
| Mon, December 31 | Festival Day | Montserrat | Public Holiday |
| Mon, December 31 | New Year´s Eve | Multiple [Show] | Multiple Types |
| Mon, December 31 | Old Year’s Night | Barbados | Observance |
| Mon, December 31 | New Year’s Eve (from noon) | Iceland | National Holiday |
| Mon, December 31 | New Year’s Eve (Bank holiday) | Andorra | Bank Holiday |
| Mon, December 31 | New Year’s Eve (from 2pm) | Brazil | Optional Holiday |
| Mon, December 31 | December 31 Bank Holiday | Japan | Bank Holiday |
| Mon, December 31 | International New Year’s Eve | Vietnam | Observance |
