He completed secondary school in Kretinga. He joined the Franciscan Order and subsequently studied at universities in Austria and Italy, where he received the degree of Doctor of Canon Law. He has been provincial of the Lithuanian Franciscan Fathers in the United States since 1964. Atviros marios (The Open seas), a collection of his poetry, was published in 1955; Saulė kryžiuose (The Sun amidst the Crosses), 1960; and Naktiginė (The Nightwatch), 1963.
A selection of his poetry was translated into English by Demo Jonaitis and published as Amene in Amber in 1968. His first book reflects the spirit of St. Francis, while the two subsequent volumes draw inspiration from Lithuanian folk art and nature. His later poetry touches on the early history of Lithuania. Andriekus excels as a poet of nature. According to Charles Angoff, who wrote a foreword to Amene in Amber, the poem "Autumn is one of the best poems to that sombre season written in the last fifty years". The prevailing tone of his poetry is a seriousness that is, according to Angoff, "aden with soft sorrow". Andriekus is at his best when he fuses his religious thought with folk symbolism and historical motifs. Saulė kryžiuose was awarded the annual prize of the Lithuanian Association for Writers in 1961.