Haruka Haruno is a first-year student at Noble Academy who dreams of becoming a princess, just like the one from her favorite picture book. Long ago, she made a promise with a boy named Kanata to never give up the dream, and he gifted her a dress-shaped key. On her first day at the academy, Haruka runs into the fairies Pafu and Aroma who came from the mystical Hope Kingdom in search of the Princess Precures to save their world from the dark witch Dyspear. Now, with the help of Princess Perfume and the Dress Up Key from Hope Kingdom's Prince Kanata, Haruka transforms into Cure Flora to protect everyone's dreams from being locked away by Dys Dark's minions.

With her friends Cure Mermaid and Cure Twinkle by her side, the three princesses join forces in battle to protect dreams, collect the 12 Dress Up Keys, and stop Dyspear's plot to turn everyone to despair.