Princess Rose welcomes Pero, the cat Puss 'n Boots, and Pierre, the young miller's son, to her kingdom. Gentle, naive, and devoted to white roses, she clings to fairy tales, anticipating a handsome prince to rescue her. Yet she summons unexpected courage, facing Lucifer, the ogre sorcerer demanding her marriage, head-on. His terrifying ultimatum—agree to wed him within three days or witness the kingdom's destruction by catastrophic darkness—drives the narrative conflict and the heroes' quest.

During Pierre's charade as a wealthy marquis, orchestrated by Pero, Rose sees past the pretense, valuing Pierre's inherent sincerity and kindness above riches or title, a stark contrast to her status-conscious father, the king. Kidnapped by Lucifer after refusing his proposal, Rose becomes the mission's focus. Pierre, Pero, and mouse bandits infiltrate Lucifer's fortress to save her. There, Rose witnesses Lucifer's horrifying transformation into a three-headed dragon, causing her to faint from shock.

Rescued and hearing Pierre's confession of his true miller origins, Rose accepts his proposal. This marriage, founded on mutual respect rather than deception, elevates Pierre from poverty to royalty and concludes Rose's arc. Her background rests on royal lineage within a politically vulnerable kingdom, but her journey centers on rejecting a forced union, recognizing true virtue in Pierre, and embracing a future built on authentic affection. Her story concludes with this union, without further elaboration in the primary film or its sequels.