The purpose of this research is to reveal the influence of Hesychastic teachings on the creation, development and the liturgical application of the church music and hymnography, through the discussion of different problems, based on written and oral testimonies, preserved till nowadays. This purpose is also achieved through an interpretation of the source materials (the liturgical, musical and hymnographic works) in the context of Orthodox belief and the teaching of the Holy Fathers, closely connected to the liturgical tradition of the Church in the 14th–15th century in terms of the teaching of Hesychasm. The depth of meaning of the musical phenomena from the tradition of the Middle Ages has been revealed based on the theological cognitive foundation – the foundation of belief. This research is based on data, connected with the liturgical Greek and Slavonic tradition and also with the mystical perception and interpretation of the musical and hymnographic works in the 13th–15th century – in the period of blossoming forth of the theological cognition of Hesychasm. The testimonies of one of the most important theological, musical and hymnographic resources from this period have been used involved in this research.