|Covid-19|January 6 – Western Europe's Great Frost of 1709, the coldest period in 500 years, begins during the night, lasting three months and with its effects felt for the entire year. In France, the coast of the Atlantic and Seine river freeze, crops fail, and 24,000 Parisians die. Floating ice enters the North Sea.
January 10 – Abraham Darby I successfully produces cast iron using coke fuel at his Coalbrookdale blast furnace in Shropshire, England.
February – In America, Mardi Gras is celebrated one more time with Masque de la Mobile in the capital of French Louisiana, Mobile, Alabama, before Mobile is moved 27 miles (43 km) down the Mobile River to Mobile Bay in 1711.
February 1 or 2 – During his first voyage, Captain Woodes Rogers encounters marooned privateer Alexander Selkirk and rescues him after four years living on one of the Juan Fernández Islands, inspiring Daniel Defoe's novel Robinson Crusoe. After sacking Guayaquil, he and Selkirk will visit the Galápagos Islands.
March 28 – Johann Friedrich Böttger reports the first production of hard-paste porcelain in Europe, at Dresden.
May – First influx into Britain of poor refugee families of German Palatines from the Rhenish Palatinate, mostly Protestants en route to the New World colonies.
June 27 (June 28 in the Swedish calendar; July 8 New Style) – Great Northern War: Battle of Poltava: In the Ukraine, Peter the Great, Tsar of Russia, defeats Charles XII of Sweden, thus effectively ending Sweden's role as a major power in Europe.
July 27 – Emperor Nakamikado accedes to the throne of Japan.
July 30 – War of the Spanish Succession: Capture of Tournai by John Churchill, 1st Duke of Marlborough and Prince Eugene of Savoy.
August 8 – The hot air balloon of Bartolomeu de Gusmão flies in Portugal.
August 28 – Pamheiba is crowned King of Manipur.
September 11 (August 31 Old Style) – War of the Spanish Succession: Battle of Malplaquet - Troops of the Dutch Republic, Habsburg Austria, the Kingdom of Great Britain and the Kingdom of Prussia led by the Duke of Marlborough drive the French from the field but suffer twice as many casualties.
October 9 – War of the Spanish Succession: British army captures Mons.
October 12 – The city of Chihuahua in Mexico is founded.
December 25 – From London, ten ships leave for the New York Colony, carrying over 4,000 people.
Trinity School is founded as the Charity School of Trinity Church in New York City.
The second Eddystone Lighthouse, erected off the south west coast of England by John Rudyerd, is completed.
Publication of the first modern edition of William Shakespeare's plays in London, edited by Nicholas Rowe.
De Nostri Temporis Studiorum Rationae (On the Study Methods of Our Times) is published by Neapolitan philosopher Giambattista Vico.
Priceless medieval altarpieces by Michael Pacher are destroyed.
January 2 – Teresia Constantia Phillips, British autobiographer (d. 1765)
February 24 – Jacques de Vaucanson, French inventor (d. 1782)
March 10 – Georg Steller, German naturalist (d. 1746)
April 14 – Charles Collé, French dramatist (d. 1783)
August 7 – Jean-Jacques Lefranc, Marquis de Pompignan, French polymath, author and poet (d. 1784)
August 8 – Tokugawa Ietsugu, 7th Tokugawa shogunate of Japan (d. 1716)
September 18 – Samuel Johnson, English writer, critic and lexicographer (d. 1784)
September 24 (bapt.) – John Cleland, English novelist (d. 1789)
October 27 (bapt.) – Thomas Alcock, English clergyman (d. 1798)
November 2 – Anne, Princess Royal and Princess of Orange, Hanoverian-born regent of Friesland (d. 1759)
December 18 – Elizabeth of Russia, empress regnant of Russia (d. 1762)
January 16 – Emperor Higashiyama of Japan (b. 1675)
January 20 – François de la Chaise, French confessor of Louis XIV of France (b. 1624)
January 24 – George Rooke, English admiral (b. 1650)
February/March – John Coode, Colonial governor of Maryland (d. 1648)
February 8 – Giuseppe Torelli, Italian composer (b. 1658)
February 9 – François Louis, Prince of Conti, French general (b. 1664)
March 9 – Ralph Montagu, 1st Duke of Montagu, English diplomat
April 8 – Wolfgang Dietrich of Castell-Remlingen, German nobleman (b. 1641)
April 21 – Gurgin Khan (George XI of Kartli), Persian Governor of Kandahar (b. 1651)
June 29 – Antoine Thomas, Belgian Jesuit astronomer in China (b. 1644)
June 30 – Edward Lhuyd, Welsh scientist (b. 1660)
July 17 – Robert Bolling, English settler in Virginia (b. 1646)
September 14 – Luis Manuel Fernández de Portocarrero, Spanish cardinal and archbishop of Toledo (b. 1635)
October 2 – Ivan Mazepa, Hetman of Ukraine (b. 1639)
October 9 – Barbara Palmer, 1st Duchess of Cleveland, English mistress of Charles II of England (b. 1640)
December 1 – Abraham a Sancta Clara, Austrian preacher (b. 1644)
December 8 – Thomas Corneille, French dramatist (b. 1625)
prob. date – Eleanor Glanville, English entomologist (born 1654)
1709 (MDCCIX) was a common year starting on Tuesday (dominical letter F) of the Gregorian calendar and a common year starting on Saturday (dominical letter B) of the Julian calendar, the 1709th year of the Common Era (CE) and Anno Domini (AD) designations, the 709th year of the 2nd millennium, the 9th year of the 18th century, and the 10th and last year of the 1700s decade. As of the start of 1709, the Gregorian calendar was 11 days ahead of the Julian calendar, which remained in localized use until 1923. In the Swedish calendar it was a common year starting on Friday, one day ahead of the Julian and ten days behind the Gregorian calendar.