The year 2003 in television involved some significant events. Below is a list of television-related events in 2003.
For the American TV schedule, see: 2003-04 United States network television schedule.

| January 17 - That's So Raven premieres on Disney Channel (2003-2007) |
| January 22 - Chappelle's Show premieres on Comedy Central (2003-2006). |
| February 4 - Posh Nosh premiers on BBC2 (2003) |
| February 21 - Da Ali G Show premiers on HBO (2003-2004) |
| March 3 - Live Prayer premiers on UPN44 (2003 - present) |
| April 6 - Sonic X premieres on TV Tokyo in Japan, later introduced to the Fox Box (now known as 4Kids TV) on September 6 (2003-2006). |
| May 17 - Megaman NT Warrior, the English-language version of Rockman EXE, premieres on Kids' WB!. |
| May 18 - State of Play (UK), a six-part serial from Paul Abbott, begins its run on BBC One, concluding on June 22. A sequel is planned for 2006. |
| May 26 - Unscrewed with Martin Sargent premieres on TechTV (now G4TV (2003-2004). |
| June 2 - Train 48 premieres on the Global Television Network in Canada (2003-2005). |
| June 27 - Dead Like Me premieres on Showtime (2003-2005). |
| July 1 - Reno 911! premieres on Comedy Central (2003-present). |
| July 8 - Big Brother 4 premieres on CBS (2000-present). |
| July 15 - Queer Eye for the Straight Guy premieres on Bravo (2003-present). |
| July 22 - Nip/Tuck premieres on FX (2003-present). |
| August 1 - My Life as a Teenage Robot premieres on Nickelodeon (2003-present). |
| August 5 - The O.C. premieres on FOX (2003-2007). |
| August 23 - ''Duck Dodgers (TV Series) premieres on Cartoon Network (2003-2005). |
| August 26 - Playmakers premieres on ESPN, and is cancelled on November 11. |
| August 29 - Cowboy U premieres on CMT (2003-present). |
| September 9 - Whoopi, with Whoopi Goldberg, premieres on NBC (2003-2004). |
| September 9 - Happy Family premieres on NBC (2003-2004). |
| September 9 - Starting Over premieres. (syndicated) (2003-2006). |
| September 11 - QI premieres on BBC in UK (2003-present). |
| September 13 - Romeo! premieres on Nickelodeon (2003-present). |
| September 14 - Carnivàle premieres on HBO (2003-2005). |
| September 15 - Eve premieres on UPN (2003-2006). |
| September 16 - Little Britain premieres on BBC in UK (2003-?). |
| September 18 - Threat Matrix premieres on ABC (2003-2004). |
| September 20 - Lilo and Stitch: The Series premieres on ABC Kids (2003-2006). |
| September 22 - Las Vegas premieres on NBC (2003-present). |
| September 22 - Two and a Half Men premieres on CBS (2003-present). |
| September 23 - I'm with Her premieres on ABC (2003-2004). |
| September 23 - NCIS premieres on CBS (2003-present). |
| September 23 - One Tree Hill premieres on the WB (2003-present). |
| September 26 - Hope and Faith premieres on ABC (2003-2006). |
| September 26 - Joan of Arcadia premieres on CBS (2003-2005). |
| September 26 - The Handler premieres on CBS (2003-2004). |
| September 28 - Cold Case premieres on CBS (2003-present). |
| September 28 - 10-8: Officers on Duty premieres (2003-2004). |
| October 1 - It's All Relative premieres on ABC (2003-2004). |
| October 1 - Karen Sisco premieres on ABC, and is cancelled on November 12 (2003-2004). |
| October 3 - Married to the Kellys premieres on ABC (2003-2004). |
| October 16 - Superstars returns to BBC One (1973-1985, 2003-2005). |
| October 26 - Viva La Bam premieres on MTV (2003-2005). |
| October 30 - Tru Calling premieres on FOX (2003-2005). |
| November 1 - Xiaolin Showdown premieres on Kids' WB! (2003-present). |
| November 2 - Arrested Development premieres on FOX (2003-2006). |
| November 7 - Star Wars: Clone Wars premieres on Cartoon Network (2003-2005). |
| November 7 - Dragonball GT premieres on Cartoon Network (2003-2005). |
| November 29 - All Grown Up!, a Rugrats spinoff, premieres on Nickelodeon (2003-2008). |
| December 8 - Battlestar Galactica premieres on Sky One in the UK (2003-present). |
| Show | Moved from | Moved to |
|---|---|---|
| Grounded for Life | FOX | The WB |
| Robot Wars | BBC Two | Five |
| Family Rosary Crusade | ABS-CBN | Studio 23 |