As punishment for the vanity of Cassiopeia, who thought herself more beautiful than the Neriads, Poseidon, god of the seas, sent a monster to the kingdom of Ethiopia. Its fury could only be detained if it received Cassiopeia's daughter, Andromeda.

This painting illustrates the moment when Perseus frees Andromeda from her bounds. He is in love with her, as is made clear by the presence of Cupid with his quiver, and later makes her his wife. Hymen, goddess of marriage, announces this engagement with her customary torch. In the background, Rubens depicts Pegasus, Perseus' steed, alongside the slain monster.

This work was commissioned by Felipe IV for the New Hall at Madrid's Alcázar Palace, as an political allegory of the power of the Spanish Monarchy. The hero, with armor that was modern in the sixteenth century, a helmet and a shield with Medusa's head, was thus a metaphor of the King himself, and of his dominion over evil.

This is one of the last paintings Rubens took on. After his death in 1640, it was finished by Jacob Jordaens.