The devotion to the Sacred Heart (also known as the Most Sacred Heart of Jesus, Sacratissimi Cordis Iesu in Latin) is one of the most widely practiced and well-known Roman Catholic devotions, taking Jesus Christ's physical heart as the representation of His divine love for humanity.

The devotion is especially concerned with what the Church deems to be the love and compassion of the heart of Christ towards humanity, and its long suffering. The origin of this devotion in its modern form is derived from a Roman Catholic nun from France, Saint Margaret Mary Alacoque, who said she learned the devotion from Jesus during a series of apparitions to her between 1673 and 1675, and later, in the 19th century, from the mystical revelations of another Roman Catholic nun in Portugal, Blessed Mary of the Divine Heart, a religious of the Good Shepherd, who requested, in the name of Christ that Pope Leo XIII consecrate the entire world to the Sacred Heart of Jesus.