In New Orleans during the vibrant Roaring Twenties, a determined young woman named Tiana has ambitious dreams of opening her very own restaurant. To fund her passion, she juggles two waitress jobs, sacrificing her social life in the process. Meanwhile, Naveen, the arrogant prince of Maldonia, arrives in the city, having been disowned by his parents and now intent on marrying Charlotte La Bouff, Tiana's best friend. Charlotte’s affluent father is throwing a lavish masquerade ball in honor of Naveen. In a stroke of luck, Charlotte hires Tiana to whip up mouthwatering beignets for this grand event, compensating her just enough to buy an old mill she dreams of converting into a restaurant.
However, Naveen and his valet Lawrence cross paths with the nefarious Dr. Facilier, an evil voodoo witch doctor who harbors ambitions to control New Orleans. With a sinister twist, Facilier transforms Naveen into a frog and turns Lawrence into his doppelganger using a voodoo talisman that contains Naveen's blood. Facilier's plan involves Lawrence marrying Charlotte and subsequently eliminating her father through dark magic to seize the La Bouff fortune.
At the extravagant ball, Tiana discovers that she has been outbid for the mill and, in a moment of embarrassment, accidentally spills food on her dress. Charlotte kindly lends her a beautiful princess costume. In a moment of despair, while wishing upon a star, Tiana encounters Naveen in his frog form. Mistaking her for a princess, he implores Tiana to kiss him, convinced that her kiss will break the curse. Reluctantly, Tiana agrees, but to her surprise, she too becomes a frog! The pair flees into the bayou, where they meet Louis, a jazz-loving alligator. After explaining their plight, Louis tells them about Mama Odie, another voodoo practitioner residing in the bayou, who might hold the key to breaking the spell.
Since Louis is unfamiliar with the route, a charming Cajun firefly named Ray lends his help to guide Tiana and Naveen. During their adventure, a budding romance develops between Tiana and Naveen, particularly as Naveen learns to take on more responsibility. Meanwhile, as tensions rise, Dr. Facilier seeks assistance from his "friends on the other side"—an army of voodoo spirits—to reclaim Naveen, offering the souls of New Orleans as a price for their aid. The spirits dispatch shadow demons to capture Tiana and her companions, but Mama Odie arrives just in time to save them.
Upon meeting Mama Odie, they discover that the spell can only be broken with a princess's kiss. Tiana realizes that since Charlotte's father has been crowned the king of Mardi Gras, Charlotte will hold the title of princess until midnight. In a hurry, the group hops onto a steamboat back to New Orleans, during which Naveen expresses his love for Tiana and reveals his intentions to propose. However, upon further reflection, he selflessly decides against it, understanding that in order for him and Tiana to regain their human forms and fund her restaurant, he must first kiss and marry Charlotte.
As fate would have it, the shadow demons manage to capture Naveen, leading him straight to Facilier, who seeks to refill the talisman with Naveen's blood. In a brave act, Ray informs Tiana about Naveen's true feelings for her, prompting her to rush to the Mardi Gras parade to find him, only to discover the disguised Lawrence marrying Charlotte.
In a heroic act of sacrifice, Ray rescues Naveen and snatches the talisman, handing it to Tiana just moments before Facilier mortally wounds him. Faced with the temptations of Facilier's offer to fulfill her dreams in exchange for the talisman, Tiana chooses honor over ambition and destroys the talisman, foiling Facilier's wicked scheme. With his plans thwarted, the spirits claim Facilier, dragging him into their realm for failing to repay his debts. Following Lawrence's arrest, Tiana confesses her love for Naveen. Charlotte, moved by their connection, agrees to kiss Naveen, enabling him and Tiana to become human again. Unfortunately, as the clock strikes midnight, Charlotte's status as a princess vanishes, leaving Tiana and Naveen as frogs.
In a bittersweet turn of events, Ray dies but is honored in a beautiful funeral arranged by Tiana and Naveen, as he is reincarnated as a star overlooking them. Eventually, Tiana and Naveen are married by Mama Odie, bestowing princess status back upon Tiana and restoring both of them to human form. Their journey culminates with their return to New Orleans, where they finalize their marriage and realize Tiana's dream of opening her restaurant.
