Saint Celestine I was pope from 422 to 432. He was a Roman and is supposed to have been a near relative of the Emperor Valentinian III. Nothing is known of his early history except that his father's name was Priscus. He is said to have lived for a time at Milan with St. Ambrose. The first notice, however, concerning him that is known is in a document of Pope Innocent I, in the year 416, where he is spoken of as Celestine the Deacon.

Various portions of the liturgy are attributed to him, but without any certainty on the subject. He held the Council of Ephesus in which the Nestorians were condemned, in 431. Four letters written by him on that occasion, dated all of them March 15, 431, together with a few others, to the African bishops, to those of Illyria, of Thessalonica, and of Narbonne, are extant in retranslations from the Greek, the Latin originals having been lost.

He actively persecuted the Pelagians, and was zealous for orthodoxy. He sent Palladius to Ireland to serve as a bishop in 431. Patricius (Saint Patrick) continued this missionary work. Celestine raged against the Novatians in Rome, imprisoning their bishop, and forbidding their worship. He was zealous in refusing to tolerate the smallest innovation on the constitutions of his predecessors, and is recognized by the church as a saint.

He died on April 6, 432. He was buried in the cemetery of St. Priscilla in the Via Salaria, but his body, subsequently moved, lies now in the Church of Santa Prassede.

In art, Saint Celestine is a pope with a dove, dragon, and flame.