Peter was born in the town of Alcantara, province of Caceres in Spain in the year 1499. His father was the governor of Alcantara, while his mother was from the Sanabia family which was one of the noble families in Alcantara. Upon completing his course in grammar and philosophy in Alcantara, he went on to study at the University of Salamanca.
In 1515, he joined the convent of the Franciscan of the Stricter Observance in Manxaretes, Extremadura, Spain and became an ordained priest in 1524. He was elected as the superior of the religious province of St. Gabriel in 1538. In 1540, he drew up the Constitutions of the Stricter Observants, but this was met with opposition and forced him to go to the mountains of Arrabida, Portugal to live a lifer of eremitical solitude. Soon after, other friars joined him and several communities were erected in the province of Arrabida. He returned to Spain in 1553 and spent two more years in solitude.
Peter provided counsel and encouragement to St. Teresa of Avila in the reform of Carmel. He also encouraged her to found her first monastery at Avila, Spain in August 24, 1562. The autobiography of St. Teresa provided the source of information regarding the life, work, the gift of miracles and prophecy of Peter.
He often went into ecstasy. He is purported to have slept for only one and a half hours each day, inside his room which had a floor area of only four and a half square feet. While in prayer and contemplation, he was often seen in ecstasies and levitation. In his deathbed, he was offered a glass of water which he refused, saying that “Even my Lord Jesus Christ thirsted on the Cross…” He died while on his knees in prayer on October 18, 1562 in a monastery at Arenas
He was beatified by Pope Gregory XV in 1622 and canonized by Clement IX in 1669. His feast day is October 19.
In 1826, St. Peter of Alcántara was named Patron of Brazil, and in 1962 (the fourth centenary of his death), of Estremadura.
In the Philippines, only 2 churches are named after him, one in Barangay Taal, Bocaue, province of Bulacan and the other in Pakil, province of Laguna.