Breakfast Princess is the princess of Breakfast Kingdom. She rules with her sister Toast Princess and her little sister Strudel Princess. They, like most princesses, are often bothered by Ice King and need Finn and Jake to get rid of him. This is implied in the beginning of "Hitman," when Breakfast Princess says "I've got another Ice King situation here."
She reappears in "Breezy," where she is seen dancing with the other princesses and later applauding Finn's dancing at Crab Princess's party.
She makes her first major appearance in "Princess Day," which centers on her issues with Lumpy Space Princess. While sarcastically praising her unparalleled self-sufficiency among the other princesses, she deliberately affronts Lumpy Space Princess about her not having a kingdom and being a bum. In order to chastise her, Lumpy Space Princess and Marceline team up to prank her and steal her music tape and car. Breakfast Princess attempts to stop them but is unintentionally run over. The two leave her in a desert and command her to build a sand castle with the shovel, to which she attempts to do so until they leave. Once they were gone, Breakfast Princess stops shoveling and walks off into the desert, leaving her fate unknown.
In "The Cooler," she appears on one of Princess Bubblegum's cameras in her surveillance room.