1739

January–March

• January 1 - Bouvet Island is discovered by French explorer Jean-Baptiste Charles Bouvet de Lozier, in the South Atlantic Ocean.
• February 24 - Battle of Karnal: The army of Iranian ruler Nader Shah defeats the forces of the Mughal emperor of India, Muhammad Shah.
• March 20 - Nader Shah occupies Delhi, India and sacks the city, stealing the jewels of the Peacock Throne, including the Koh-i-Noor.

  April–June

• April 7 - English highwayman Dick Turpin is executed by hanging for horse theft.
• May 12 - John Wesley lays the foundation stone of the New Room, Bristol in England, the world's first Methodist meeting house.
• June 2 - The Royal Swedish Academy of Sciences is founded in Stockholm, Sweden.

  July–September

• July 9 - The first group purporting to represent an all-England cricket team, consisting of 11 players from various parts of England, comes to Kent and loses to the renowned Kent team, led by Lord John Sackville.
• July 12 - The British East India Company signs a treaty with the Maratha Empire to gain the right of free trade within the territory.
• July 22 - the Ottoman Empire retakes Belgrade from Austria's Habsburg Monarchy after winning the Battle of Grocka.
• August 20 - The Viceroyalty of New Granada, incorporating modern-day Colombia, Ecuador, and Venezuela is re-established by the royal cedula of King Philip V of Spain, 16 years after it had been dissolved, and adds the territory of Panama as well.
• September 9 - The Stono Rebellion, a slave rebellion, erupts near Charleston, South Carolina.
• September 18 - The Treaty of Belgrade brings the Austro-Russian–Turkish War to an end.

  October–December

• October 3 - The Treaty of Niš is signed.
• October 17 - The Foundling Hospital is created in London by royal charter.
• October 23 - War of Jenkins' Ear: Great Britain declares war on Spain.
• November 20-22 - War of Jenkins' Ear - Battle of Porto Bello: British marine forces capture the Panamanian silver exporting town of Portobelo from the Spanish.
• December 30- Months of unseasonably cold weather begin in Ireland, precipitating the Irish Famine of 1740, known as Bliain an Áir. A January 5 dispatch from Dublin to the Stamford Mercury says "Since last Wednesday we have had the most violent cold Weather that was ever known in this Kingdom; hard Frost began that evening, which has continued ever since with a very stormy Wind at South-East." At least 13% of Ireland's population dies of starvation in the year that follows.

  Date unknown

• Ecuador becomes a part of New Granada.
• 84,000 farmers revolt in the province of Iwaki in Japan.
• A Plinian eruption of Mount Tarumae volcano occurs in Japan.
• The first Bible in Estonian is published.