In New Orleans, Tiana is a young waitress who dreams of owning her own restaurant, an aspiration she inherited from her late father. Despite working two jobs, she struggles to save enough money to make her dream a reality. Meanwhile, Prince Naveen of Maldonia arrives in the city seeking a wealthy bride to maintain his lifestyle, as his parents have cut him off financially. However, Naveen is transformed into a frog by the villainous Dr. Facilier, a voodoo witch doctor, who has made a dark deal with shadowy entities to gain control of the city.

At a masquerade ball, Tiana, wearing a borrowed princess gown, encounters Naveen as a frog. Believing she is a princess due to her attire, Naveen persuades Tiana to kiss him, hoping to break the spell. However, the kiss does not have the desired effect, and instead, Tiana is also turned into a frog. The two flee into the bayou to seek a way to reverse their curse and encounter an array of characters, including a lovesick Cajun firefly and an alligator with a passion for jazz. Their journey becomes an adventure as they navigate the challenges of the swamp and their own developing relationship.