The year 1703 (MDCCIII) started on a Monday, (or a Thursday by the 11-day slower Julian calendar).

Events 

 St. Petersburg becomes the capital of Russia

 February 2 – an earthquake hit the town of L'Aquila, Italy.
 February 4 – in Japan, the 47 samurai (47 Ronin) commit seppuku, a ritual suicide.
 February 14 – an earthquake hits the city of Norcia, Italy.
 February – soldiers at Fort Louis de la Mobile celebrate Mardi Gras in Mobile, starting the tradition for Mobile, Alabama.
 April 21 – the Company of Quenching of Fire (i.e., a fire brigade) was started in Edinburgh, Scotland.
 May 27 – the founding of St Petersburg in Russia. 
 May 26 – Portugal joins the Grand Alliance.
 July 29 to 31 – Daniel Defoe is placed in a pillory then imprisoned 4 months for the crime of libel, after publishing a satirical pamphlet (his release is granted mid-November).
 September 12 – the War of the Spanish Succession started in Habsburg, when Archduke Charles was proclaimed King of Spain.
 October – a whirlwind blows down the tower of the Gan Takal in Gondar, the capital of Ethiopia, killing 30 people.
 November 19 – an Unknown masked prisoner dies in Bastille.
 November 24 to December 2 – the Great Storm of 1703, an Atlantic hurricane, blowes through southern England and the English Channel, killing nearly 8000, mostly at sea.
 December 27 – Portugal and England sign the Methuen Treaty which gives preference to Portuguese imported wines into England.

Undated 
 A Tale of a Tub, first major satire by Jonathan Swift, is published.
 George Psalmanazar arrives in London.
 Isaac Newton becomes the chairman of the Royal Society.
 Ahmed III (1703-1730) succeeds Mustafa II (1695-1703) as emperor of the Ottoman Empire.

Births 

 February 5 – Gilbert Tennent, Irish-born religious leader, was born (he died in 1764)
 March 5 – (N. S.) Vasily Kirillovich Trediakovsky, a Russian poet, was born (he died in 1768)
 May 14 – David Brearly, a delegate to the U.S. Constitutional Convention, was born (he died in 1785)
 June 17 – John Wesley, the English founder of Methodism, was born (he died in 1791)
 June 26 – Thomas Clap, the first president of Yale University was born (he died in 1767)
 August 2 – Lorenzo Ricci, the Italian Jesuit leader was born (he died in 1775)
 September 29 – François Boucher, a French painter was born (he died in 1770)
 October 5 – Jonathan Edwards, an American preacher was born (he died in 1758)
 October 28 – Antoine Deparcieux, a French mathematician was born (he died in 1768)
 November 25 – Jean-François Séguier, a French astronomer and botanist was born (he died in 1784)
 November 26 – Theophilus Cibber, an English actor and writer was born (he died in 1758)
 December 2 – Ferdinand Konščak, a Croatian explorer was (he died in 1759)

Deaths 
 January 11 – Johann Georg Graevius, German classical scholar and critic died (born 1632)
 March 3 – Robert Hooke, a very important English scientist died (born 1635)
 March 31 – Johann Christoph Bach, German composer died (born 1642)
 April 20 – Lancelot Addison, English royal chaplain died (born 1632)
 May 16 – Charles Perrault, French writer died (born 1628)
 May 26 – Samuel Pepys, English civil servant and diarist died (born 1633)
 June 14 – Jean Herauld Gourville, French adventurer died(born 1625)
 July 17 – Roemer Vlack, Dutch naval commander died (birthdate unknown)
 September 22 – Vincenzo Viviani, Italian mathematician and scientist died (born 1622)
 September 25 – Archibald Campbell, 1st Duke of Argyll, Scottish privy councillor died (born 1658)
 September 29 – Charles de Saint-Évremond, French soldier died (born 1610)
 October 28 – John Wallis, English mathematician died (born 1616)
 November 19 – The Man in the Iron Mask died
 November 30 – Nicolas de Grigny, French organist and composer died (born 1672)
 December 28 – Mustafa II, Ottoman Sultan (born 1664) died
 date unknown Phetracha, king of Ayutthaya died (born 1632)