Maria Beatrice was born at the Ducal Palace of Modena. She was the only daughter of Ercole III of Modena and Maria Teresa Cybo-Malaspina, ruling Duchess of Carrara and Massa. Three years after her birth, her mother gave birth to a son who died aged 5 months in May 1753. Her parents were part of an unhappy marriage which made the chance of having another son very unlikely. Her parents separated and Maria Beatrice was soon acknowledged as an heiress to four sovereign duchies.