The magic notebook is a notebook with a black cover which shows a golden Cartoon Network logo. The book contains multiple blank white pages that can be written in.
The notebook has the ability to make anything the user writes/draws in it become real, as demonstrated by Sarah in "The Shippening," when she writes fanfiction and draws fanart/original characters while Gumball and Darwin stumble upon the likes of her doing through the power of the notebook. The notebook takes written content very literally as any metaphors made in the text are translated into reality, sometimes with horrific results. This is also the case with pieces of art drawn in the book as when a ripped out page is ruined, the same effect happens to the character in reality. People affected by the book seem to be aware of the book's doing, yet their feelings can be manipulated by it.
- The notebook has the Cartoon Network logo engraved in its cover, thus breaking the fourth wall.
- The notebook could be a reference to Maxwell's notebook from the Scribblenauts series, as both notebooks allow anything written in them to come into existence.