This is a list of notable events, premieres, releases, series cancellations and endings and other business ventures for Nickelodeon in the year 2009. To many fans, this is when Nickelodeon started to decline in terms of programming and quality.
- January 26 - Olivia
- March 28 - The Penguins of Madagascar, after the 2009 Nickelodeon Kids' Choice Awards.
- May 11 - Dino Dan
- August 24 - The Fresh Beat Band
- September 18 - The Troop
- September 28 - BrainSurge
- November 7 - Fanboy and Chum Chum
- November 28 - Big Time Rush
- January 24 - Tak and the Power of Juju
- May 2 - My Life as a Teenage Robot, three seasons
- May 23 - Mr. Meaty, three seasons
- June 13 - The Naked Brothers Band, three seasons
- May 1-3 - The Fairly OddParents: "Wishology"
- May 9 - iCarly: "iDate A Bad Boy"
- August 8 - iCarly: "iFight Shelby Marx"
- November 28 - Big Time Rush: "Big Time Audition"
- December 5 - iCarly: "iQuit iCarly"
Australian TV series
- February 2 - The Nick Jr. and TEENick blocks end on Nickelodeon in preparation for the channel rebrandings. The Nick Jr. block is renamed Play Date while both Saturday and Sunday TEENick remain unnamed as of 2012.
Home video releases
- January 27 - SpongeBob SquarePants: Spongicus
- February 2 - The Penguins of Madagascar
- February 3 - Gym Teacher: The Movie
- February 24 - The Mighty B!: We Got the Bee
- March 3 - SpongeBob SquarePants: SpongeBob vs. The Big One
- March 31 - Spectacular
- April 7 - SpongeBob SquarePants: 10 Happiest Moments
- April 21 - iCarly: Season 1, Volume 2
- July 21 - SpongeBob SquarePants: To SquarePants or Not To SquarePants
- August 18 - iCarly: Season 2, Volume 1
- October 6 - Dora the Explorer: Dora's Christmas
- November 10 - SpongeBob SquarePants: Truth or Square
- December 8 - SpongeBob SquarePants: Season 6, Volume 1
- June 2
- The Fairly OddParents: Season 1
- The Fairly OddParents: Season 2
- Rugrats: Season 1
- Rugrats: The Best of Season 2
- June 9 - Making Fiends: Season 1
- November 24 - The Best of Rocko's Modern Life: Volume 3
- December 8
- Doug: Season 3
- The Mighty B!: BEEing Bessie Higgenbottom
- December 22 - Doug: The Best of Season 4
- February 8 - H2O: Just Add Water: Season One
- February 9 - H2O: Just Add Water: Season Two
- February 23
- March 2 - Back at the Barnyard: Season Two
- April 13 - Yo Gabba Gabba: Season Two
- April 20 - Ren & Stimpy: The Best of Ren & Stimpy, Volume One
- May 2
- The Fairly OddParents: Season Five
- The Fairly OddParents: Wishology
- June 1 - Ren & Stimpy: The Best of Ren & Stimpy, Volume Two
- June 22
- June 29 - Ren & Stimpy: The Best of Ren & Stimpy, Volume Three
- July 20 - SpongeBob SquarePants: Season Seven
- August 3 - Rocko's Modern Life: Best of Volume Two
- August 17 - Ni Hao, Kai-Lan: Season Two
- August 24 - The Fresh Beat Band: Season One
- September 14 - iCarly: Volume Three
- October 26 - H2O: Just Add Water: Season Three
- November 14 - True Jackson, VP: Season Two
- November 28 - Big Time Rush: Season One
- February 24 - Nickelodeon announces they would be rebranding Noggin as Nick Jr. and The N as TeenNick and Nicktoons Network as simply Nicktoons on September 28th.
- April 23 - Dish Network removed Nick GaS from their lineup (at Channel 177) to make room for the west coast feed of Cartoon Network. This was a delayed reaction after having problems removing it since the channel's dissolution
- May 6 - Noggin and The N both debuted on Dish Network as 24/7 television channels.
- September 28 - The channel rebrandings are accompanied by the debut of new logos for all Nickelodeon channels, including Nick at Nite.
- October 21 - Nickelodeon secures the rights to the Teenage Mutant Ninja Turtles franchise from Mirage Studios.
- December - Nickelodeon Magazine publishes its final issue and is discontinued.