She was born Alessandra Lucrezia Romola de' Ricci in Florence to Pier Francesco de' Ricci, of a patrician family, and his wife, Caterina Bonza, who died soon after. At age 6 or 7, her father enrolled her in a school run by a monastery of Benedictine nuns in the Monticelli quarter of the city, near their home, where her aunt, Luisa de' Ricci, was the abbess. She was a very prayerful person from a very young age. There she developed a lifelong devotion to the Passion of Christ. After a short time outside the monastery she entered the Convent of St Vincent in Prato, Tuscany, a cloistered community of Religious Sisters of the Third Order of St. Dominic, disciples of the noted Dominican friar Girolamo Savonarola, who followed the strict regimen of life she desired. In May 1535 she received the religious habit from her uncle, Friar Timoteo de' Ricci, O.P., who was confessor to the convent, and the religious name of Catherine, after the Dominican tertiary, Catherine of Siena.
De' Ricci's period of novitiate was a time of trial. She would experience ecstasies during her routine, which caused her to seem asleep during community prayer services, dropping plates and food, so much so that the community began to question her competence, if not her sanity. Eventually the other Sisters became aware of the spiritual basis for her behavior. By the age of 30 she had risen to the post of prioress.
She is reported to have been a nun with visions, states Constance Classen, who miraculously held baby Jesus dressed in swaddling clothes, and was mystically married and united with adult Jesus.
As the prioress, De' Ricci developed into an effective and greatly admired administrator. She was an advisor on various topics to princes, bishops and cardinals. She corresponded with three figures who were destined to become popes: Pope Marcellus II, Pope Clement VIII, and Pope Leo XI. An expert on religion, management and administration, her advice was widely sought. She gave counsel both in person and through exchanging letters. It is reported that she was extremely effective and efficient in her work, managing her priorities very well.
It is claimed that De' Ricci's meditation on the Passion of Christ was so deep that she spontaneously bled, as if scourged. She also bore the Stigmata. During times of deep prayer, like Catherine of Siena, her patron saint, a coral ring representing her marriage to Christ, appeared on her finger.
It is reported that De' Ricci wore an iron chain around her neck, engaged in extreme fasting and other forms of penance and sacrifice, especially for souls in Purgatory.
One of the miracles that was documented for her canonization was her appearance many hundreds of miles away from where she was physically located. This involved appearing in a vision St Philip Neri, a resident of Rome, with whom she had maintained a long-term correspondence. Neri, who was otherwise very reluctant to discuss miraculous events, confirmed the event.
De' Ricci lived in the convent until her death in 1590 after a prolonged illness. Her remains are visible under the altar of the Minor Basilica of Santi Vicenzo e Caterina de' Ricci, Prato, which is next to the convent associated with her life.
De' Ricci was beatified by Pope Clement XII in 1732, and canonized by Pope Benedict XIV in 1746. Her feast day falls on 13 February.