1903 in sports describes the year's events in world sport.
- Ohio League championship – Massillon Tigers
- "US Pro Football Title" – Franklin Athletic Club
- Western Pennsylvania Championship – Latrobe Athletic Association
- 1902–03 World Series of Football champion – Syracuse Athletic Club
- 1903 World Series of Football champion – Franklin Athletic Club
- 1 January – the Syracuse Athletic Club defeated the Orange Athletic Club, 36–0, to win the 1902–03 World Series of Football, held at Madison Square Garden.
- 3 September – the Massillon Tigers of the "Ohio League" are established in Massillon, Ohio.
- 17 December – the Franklin Athletic Club defeated the Watertown Red & Black, 12–0, to win the 1903 World Series of Football, held at Madison Square Garden.
- The Football League – The Wednesday 42 points, Aston Villa 41, Sunderland 41, Sheffield United 39, Liverpool 38, Stoke 37
- FA Cup final – Bury 6–0 Derby County at Crystal Palace, London. This remains the record scoreline in an FA Cup final.
- National Championship – VfB Leipzig 7—2 DFC Prag at Hamburg-Altona (after extra time)
- The 1903 German football championship is the first to be sanctioned by the Deutscher Fußballbund (DFB). Until the formation of the Bundesliga in 1963, the championship format is based on a knockout competition, contested between the winners of each of the country's top regional leagues.
- Scottish Football League – Hibernian
- 1903 Scottish Cup final – Rangers 2–0 Hearts at Celtic Park (second replay after 1–1 and 0–0 draws previously)
- Collingwood wins the 7th VFL Premiership: Collingwood 4.7 (31) d Fitzroy 3.11 (29) at Melbourne Cricket Ground (MCG)
- 1–13 October — inaugural World Series is played between the winners of the National and American Leagues. Boston Americans (AL) defeats Pittsburgh Pirates (NL) by 5 games to 3.
- New York Yankees founded.
- Northern League championship – Winnipeg Maroons win a second consecutive minor leagues title.
- Having previously held the World Middleweight Championship and the World Heavyweight Championship, Bob Fitzsimmons wins his third world title when he captures the World Light Heavyweight Championship.
- The inaugural World Light Heavyweight Champion is Jack Root of Bohemia following his ten-round victory over Charles "Kid" McCoy at Detroit on 22 April. Root's title is short-lived as he loses on 4 July to George Gardiner at Fort Erie, Ontario. Gardner wins by a technical knockout after 12 rounds. On 25 November, Gardner loses the title to Fitzsimmons after 20 rounds at San Francisco. Fitzsimmons retains the title until 1905.
- Young Corbett II vacates the World Featherweight Championship. The vacant title is won by Abe Attell who defeats Johnny Reagan at St Louis in the 20th round. Attell is one of the great champions and holds the title until 1912.
- Frankie Neil defeats Harry Forbes in San Francisco by a second-round knockout to take the World Bantamweight Championship, which he holds for one year.
Lineal world champions
- World Heavyweight Championship – James J. Jeffries
- World Light Heavyweight Championship – new title → Jack Root → George Gardiner → Bob Fitzsimmons
- World Middleweight Championship – Tommy Ryan
- World Welterweight Championship – Barbados Joe Walcott
- World Lightweight Championship – Joe Gans
- World Featherweight Championship – Young Corbett II → vacant → Abe Attell
- World Bantamweight Championship – Harry Forbes → Frankie Neil
- County Championship – Middlesex
- Minor Counties Championship – Northamptonshire
- Most runs – C B Fry 2683 @ 81.30 (HS 234)
- Most wickets – Wilfred Rhodes 193 @ 14.57 (BB 8–61)
- Wisden Cricketers of the Year – Colin Blythe, John Gunn, Albert Knight, Walter Mead, Plum Warner
- Sheffield Shield – New South Wales
- Most runs – Reggie Duff 786 @ 87.33 (HS 194)
- Most wickets – Jack Saunders 32 @ 20.81 (BB 8–106)
- Inter-Colonial Tournament – not contested
Tour de France
World Figure Skating Championships
- Grand National – Drumcree
- 1,000 Guineas Stakes – Quintessence
- 2,000 Guineas Stakes – Rock Sand
- The Derby – Rock Sand
- The Oaks – Our Lassie
- St. Leger Stakes – Rock Sand
- Melbourne Cup – Lord Cardigan
- King's Plate – Thessalon
- Montreal HC defeats Winnipeg Victorias three games to one in a cup challenge.
- Montreal HC and Ottawa HC tie for first place in the Canadian Amateur Hockey League (CAHL) regular season with 6–2 records. The teams play off for the CAHL championship and Stanley Cup. Ottawa defeats Montreal 9–1 in a two-game, total-goals series to win its first Stanley Cup title.
- Ottawa HC defeats Rat Portage Thistles two games to nil in another cup challenge.
- Ottawa Silver 7 sweep Montréal AAA in 2 games
- First ice hockey league in Europe begins, contested by five teams from Princes Skating Club and Hengler's Ice Rink, both in London.
- The Paris-Madrid Trail is run on 24 May with a scheduled distance of 1014 km. It is a disastrous event which causes at least eight deaths including those of drivers Marcel Renault and Claude Barrow. The race is stopped by the authorities at Bordeaux. It is in retrospect sometimes referred to as the VIII Grand Prix de l'ACF. Fernand Gabriel (France) is the first to reach Bordeaux in his Mors.
- Road racing is banned as a result and the legacy of the event is the introduction of circuits, the first being opened at Le Mans in 1906 for the inaugural French Grand Prix, organised by the Automobile Club de France (ACF).
Gordon Bennett Cup
- Fourth running of the Gordon Bennett Cup takes place in Ireland due to road racing being illegal in Great Britain, the scheduled host. The location is the roads around Athy, County Kildare, and the winner is Camille Jenatzy (Belgium) driving a Mercedes
- It is at the 1903 Gordon Bennett cup that international racing colours are formally adopted with Italy taking red, Germany white, France blue and Great Britain taking its British racing green (BRG) for the first time. The British choice of green is partly due to the event being held in Ireland, which at the time is part of the UK, and to precedent as the winning Napier of 1902 had been painted olive green.
- Second running of the Ardennes Circuit race around Bastogne is won by Pierre de Crawhez driving a Panhard-Levassor 70 hp in a time of 5:52:07. The total distance is 512.05 km (85.34 km x 6 laps).
The Boat Race
- Championship – Halifax
- Challenge Cup final – Halifax 7–0 Salford at Headingley Rugby Stadium, Leeds
- Lancashire League Championship – not contested
- Yorkshire League Championship – not contested
Home Nations Championship
Speed Skating World Championships
- Men's All-round Champion – none declared
- Wimbledon Men's Singles Championship – Laurence Doherty (GB) defeats Frank Riseley (GB) 7–5 6–3 6–0
- Wimbledon Women's Singles Championship – Dorothea Douglass Lambert Chambers (GB) defeats Ethel Thomson Larcombe (GB) 4–6 6–4 6–2
- French Men's Singles Championship – Max Decugis (France) defeats André Vacherot (France): details unknown
- French Women's Singles Championship – Françoise Masson (France) defeats Kate Gillou (France) 6–0 6–8 6–0
- American Men's Singles Championship – Laurence Doherty (GB) defeats William Larned (USA) 6–0 6–3 10–8
- American Women's Singles Championship – Elisabeth Moore (USA) defeats Marion Jones (USA) 7–5 8–6
- 1903 International Lawn Tennis Challenge – British Isles 4–1 United States at Longwood Cricket Club (grass) Boston, United States
- The New York Yacht Club retains the America's Cup as Reliance defeats British challenger Shamrock III, of the Royal Ulster Yacht Club, 3 races to 0 (Shamrock III abandoned the third race)
- "Scottish Cup Past Winners | Scottish Cup | Scottish FA". www.scottishfa.co.uk. Retrieved 5 February 2021.
- Boston Athletic Association (2011). "Boston Marathon History: 1901-1905". www.baa.org. Boston: Boston Athletic Association. Archived from the original on 2011-02-21. Retrieved March 2, 2011.
- Cyber Boxing Zone
- "Cycling-Tour de France list of winners". Eurosport UK. 26 August 2020. Retrieved 18 February 2021.
- "Epsom Derby | History, Winners, & Facts | Britannica". www.britannica.com. Retrieved 30 December 2021.
- 1903 Grand Prix and Paris Races Archived 2013-05-14 at the Wayback Machine. Retrieved on 12 September 2009.
- The St. Louis Republic September 04 1903 Reliance Alone Finishes Last Race For Cup