He was born February 7 in the little village of St. John Karystia, in the province of Evia. His parents, Leonidas and Eleni Bairaktaris (daughter of Antonios Lambrou), baptized him Evangelos. He was fourth out of five siblings.
He was tonsured a monk at the age of fourteen or fifteen with the monastic name Nikitas. He served in the Athonite skete of Kafsokalyvia, in the Cell of St. George, under two spiritual fathers: Fr. Panteimon and Fr. Ionnakios. Forced by pleurisy to depart the Holy Mountain, he returned to his birthplace, where he was unexpectedly elevated to the priesthood at the age of 21 by Porphyrios III, Archbishop of Mount Sinai and Raithu.
With the outbreak of World War II he became a hospital chaplain in Athens, in which post he continued for three decades (1940–1970). His later years were devoted to the construction of the Holy Convent of the Transfiguration of the Savior.
After 1984 he returned to Mount Athos, occupying the same cell which he had earlier in life been forced to abandon. Through his role as spiritual father, Elder Porphyrios became known to an ever-wider circle of Orthodox followers. Several compilations of stories and sayings attributed to him have been published.
His sainthood was declared by the synod of the Ecumenical Patriarchate on November 27, 2013. In 2017 the holy synod of the Romanian Orthodox Church formally approved the inclusion of St. Porphyrios the Kavoskalyvite into the Church’s calendar on December 2 as well, including his troparion, kontakion, Synaxarion, and icon.