The most significant source for the devotion to the Sacred Heart in the form it is known today was Visitandine Saint Marharet Mary Alacoque (1647-1690), who claimed to have received visions of Jesus Christ. There is nothing to indicate that she had known the devotion prior to the revelations, or at least that she had paid any attention to it. These alleged revelations were numerous, and the following apparitions are especially remarkable:

• On December 27, probably 1673, the feast of Saint John, Margaret Mary reported that Jesus permitted her, as He had formerly allowed Saint Gertrude, to rest her head upon His Heart, and then disclosed to her the wonders of His love, telling her that He desired to make them known to all mankind and to diffuse the treasures of His goodness, and that He had chosen her for this work.
• In probably June or July, 1674, Margaret Mary claimed that Jesus requested to be honored under the figure of His Heart of flesh, also claiming that, when He appeared radiant with love, He asked for a devotion of expiatory love: frequent reception of Communion, especially Communion on the First Friday of the month, and the observance of the Holy Hour.
• During the octave of Corpus Christi, 1675, probably on June 16, the vision known as the "great apparition" reportedly took place, where Jesus said, "Behold the Heart that has so loved men ... instead of gratitude I receive from the greater part (of mankind) only ingratitude ...", and asked Margaret Mary for a feast of reparation of the Friday after the octave of Corpus Christi, bidding her consult Father de la Colombière, then superior of the small Jesuit house at Paray. Solemn homage was asked on the part of the king, and the mission of propagating the new devotion was especially confided to the religious of the Visitation and to the priests of the Society of Jesus.

A few days after the "great apparition", Margaret Mary reported everything she saw to Father de la Colombière, and he acknowledging the vision as an action of the spirit of God, consecrated himself to the Sacred Heart and directed her to write an account of the apparition. He also made use of every available opportunity to circulate this account, discreetly, through France and England. At his death, February 15, 1682, there was found in his journal of spiritual retreats a copy in his own handwriting of the account that he had requested of Margaret Mary, together with a few reflections on the usefulness of the devotion. This journal, including the account and an "offering" to the Sacred Heart, in which the devotion was well explained, was published at Lyons in 1684. The little book was widely read, even at Paray. Margaret Mary reported feeling "dreadful confusion" over the book's contents, but resolved to make the best of it, approving of the book for the spreading of her cherished devotion. Outside of the Visitandines, priests, religious, and laymen espoused the devotion, particularly a Cappuchin, Margaret Mary's two brothers, and some Jesuits, among the latter being Fathers Croiset and Gallifet, who promoted the devotion.

In 1693 the Holy See imparted indulgences to the Confraternities of the Sacred Heart and, in 1697, granted the feast to the Visitandines with the Mass of the Five Wounds. It would not be until 1765 the feast was received quasi-officially by the episcopate of France at the request of the Queen. Finally, in 1856, at the urgent entreaties of the French bishops, Pope Pius IX extended the feast to the Catholic Church under the rite of double major. In 1889 it was raised by the Catholic Church to the double rite of first class.