He was a famous preacher, and many of his homilies, including a series of Lenten lectures on The Six Days of Creation (Gr. Hexaëmeron), and an exposition of the psalter, have been preserved. Some, like that against usury and that on the famine in 368, are valuable for the history of morals; others illustrate the honor paid to martyrs and relics; the address to young men on the study of classical literature shows that Basil was lastingly influenced by his own education, which taught him to appreciate the importance of the classics as preparatory instruction.

His ascetic tendencies are exhibited in the Moralia and Regulae, ethical manuals for use in the world and the cloister respectively. Of the monastic rules traced to Basil, the shorter is the one most probably his work.

It is in the ethical manuals and moral sermons that the practical aspects of his theoretical theology are illustrated. So, for example, it is in his Sermon to the Lazicans that we find Basil explaining how it is our common nature that obliges us to treat our neighbor's natural needs (e.g., hunger, thirst) as our own, even though he is a separate individual. Later theologians explicitly explain this as an example of how the saints become an image of the one common nature of the persons of the Trinity.

His three hundred letters reveal a rich and observant nature, which, despite the troubles of ill-health and ecclesiastical unrest, remained optimistic, tender and even playful. His principal efforts as a reformer were directed towards the improvement of the liturgy, and the reformation of the monastic orders of the East.

Most of the liturgies bearing the name of Basil, in their present form, are not primarily his work, but they nevertheless preserve the recollection of Basil's activity in this field in formularizing liturgical prayers and promoting church-song. One liturgy attributed to him is The Divine Liturgy of Saint Basil the Great, a liturgy that is somewhat longer than the more commonly used Divine Liturgy of Saint John Chrysostom; it is still used on certain feast days in the Church, such as every Sunday of Great Lent and January 1, on which his memory is celebrated.