Year 1797 (MDCCXCVII) was a common year starting on Sunday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Thursday of the 11-day slower Julian calendar).

Events of 1797

January - February

• January 1 - New Year Eve Party with the invention of confetti and party hats.
• January 3 - The Treaty of Tripoli (a peace treaty between the United States and Tripoli) is signed at Algiers. see also 1796.
• January 7 - The parliament of the Cisalpine Republic adopts the Italian green-white-red tricolour as official flag. It is the birthday of the flag of Italy.
• January 15 - London haberdasher John Hetherington wears silk top hat in public and attracts a large crowd of onlookers. He is later fined £500 for causing public nuisance.
• February 14 - The Battle of Cape St. Vincent (1797), part of the Wars of the French Revolution.
• February 18 - Spanish Governor Chacón peacefully surrenders the colony of Trinidad to a British naval force commanded by Sir Ralph Abercromby.
• February 22 - The Last invasion of Britain begins. French forces under the command of American Colonel William Tate land near Fishguard in Wales.
• February 25 - Tate surrenders to the British at Fishguard.
• February 26 - The Bank of England (national bank of Britain) issues the first one-pound and two-pound notes (discontinued March 11 1988).

March - June