Iolanta, the blind daughter of the King of Provence, is telling her nurse, Martha, that she is full of some unknown longing. Iolanta's friends, Brigitte and Laura, try to cheer her up by singing songs and bringing her flowers. Martha also tries to comfort Iolanta by singing her favorite lullaby. This sends Iolanta to sleep.

Enter Alméric, King René's sword-bearer. He informs the castle porter, Bertrand, that very soon the King will be arriving with a famous Physician who, it is hoped, will cure Iolanta's blindness. The trumpets sound, announcing the arrival of the King. King René enters accompanied by the Moorish Physician, Ibn-Hakia. The King explains that Iolanta has been betrothed from infancy to Robert, Duke of Burgundy, and is soon to marry him, but the Duke does not know that his future wife is blind. Indeed, Iolanta herself is totally unaware of her misfortune. Iolanta has been brought up by her father in this remote castle. He surrounded her with loyal retainers and forbade them on pain of death to tell her the truth. Ibn-Hakia says that the only hope for Iolanta is to inform her of her disability and then, so long as she passionately wishes to recover her sight, she will do so. King René is full of doubts and fear for his daughter's future.