Prince Siegfried is a young royal who encounters Princess Odette transformed into a swan on a lake. Intervening to prevent his companion from shooting her, he finds himself captivated by her presence despite her avian form. Following her, he witnesses her transformation into a human and learns of the curse placed upon her by the sorcerer Rothbart, confining her to swan form by day unless broken by a vow of true love.

Demonstrating immediate determination, Siegfried pursues Odette and invites her to his birthday ball, intending to choose her as his bride. Despite her initial reluctance, his intense emotional connection—described as feeling "something for her the moment he saw her eyes"—persuades her to attend, underscoring his headstrong and romantic nature.

His commitment is tested at the ball when Rothbart and his daughter Odile orchestrate a deception. Magically disguised as Odette, the more overtly seductive Odile captivates Siegfried, leading him to mistakenly pledge his love and loyalty to her. He realizes his grave mistake only upon hearing Rothbart's triumphant laughter and witnessing the real Odette's despair.

In the ensuing confrontation at Rothbart's castle, Siegfried battles the sorcerer to rescue Odette. When Rothbart gains the upper hand and threatens Siegfried's life, Odette offers to marry Rothbart in exchange for the prince's safety. Unwilling to allow Odette eternal captivity, Siegfried seizes Rothbart's sword and impales himself. This act of self-sacrifice triggers a surge of light that destroys Rothbart and Odile, nullifying all of Rothbart's enchantments. The curse on Odette and the other victims breaks, restoring those like Adolf who had been transformed into statues.

Siegfried survives the collapse of Rothbart's castle and reunites with Odette. Observers within the narrative, such as the squirrels Hans and Margarita, note his devotion was instrumental in breaking the curse.