2012

1

 * Looney Tunes New Year's Day Marathon aired.

11

 * Lego Ninjago: Masters of Spinjitzu premieres on television.

24

 * Level Up  premieres.

7

 * The Looney Tunes Show airs it's season one finale.

13

 * Adventure Time airs it's season three finale.

17

 * Secret Mountain Fort Awesome airs its 18th episode and is the last to air before Cartoon Network removed it from its schedule afterwards due to poor ratings, as one character, Uncle Grandpa, spun-off into his own show one year later.

3

 * Teen Titans returns with a new shorts with DC Nation!
 * DC Nation premieres as a new programing block for Saturday mornings the remaining new episodes of season one of Young Justice and the series premiere of Green Lantern: The Animated Series (Warner Bros Animation first CGI animated series ever created), along with some new DC Nation Shorts during commercial break.

13

 * The Amazing World of Gumball airs it's season one finale.

19

 * Ben 10 Week aired, from March 19 to 23.

30

 * Cartoon Planet revives after its 14 year cancellation.

1

 * Scaredy Squirrel returns to the network for one day in place of Looney Tunes at 6:00am and again at 11:45 am.

2

 * Adventure Time begins its fourth season.

21

 * Young Justice airs its season one finale.

28

 * Young Justice airs its season two premiere under the new title Young Justice Invasion.

28

 * Adventure Time Memorial Day Marathon aired.

5

 * Total Drama airs it forth season.

4

 * Cartoon Network's second newer feed in nowadays, Canadian feed launched.

7

 * Sensei Wu-Woo Weekend aired until July 8th.

30

 * Scooby-Doo! Mystery Incorporated  begins it's second and final season.

7

 * The Amazing World of Gumball begins it's second season.

28

 * Total Drama ends season four as a 1 hour finale.

3

 * Regular Show airs it's season three finale.

22

 * Ben 10: Omniverse premieres.

1

 * Cartoon Network turns 20 years old
 * Regular Show’s fourth season starts.

2

 * The Looney Tunes Show air it's second and final season.

22

 * Adventure Time airs it's season four finale.

12

 * Adventure Time launches its fifth season.

21

 * LEGO Ninjago: Season 2 Finale Marathon aired, from 7AM to 8PM.

22

 * Looney Tunes Thanksgiving Day Marathon aired.

23

 * Ben 10 Omni-a-Thon aired.

3

 * Christmas Special Week aired from December 3 to 25.

31

 * Incredible Crew New Year's Eve Marathon aired, from 6AM to 9PM.