Once, around the year 518, while serving in the Church of the Panagia at Blachernae, during the All-Night Vigil for the Feast of the Nativity of Christ, he was assigned to read the kathisma verses from the Psalter.

He immediately received a blessing from the Patriarch, mounted the ambo (pulpit), and chanted extemporaneously his famous Kontakion of the Nativity, "Today the Virgin gives birth to Him Who is above all being…."

The emperor, the patriarch, the clergy, and the entire congregation were amazed at both the profound theology of the hymn and Romanos' clear, sonorous voice as he sang.

Arresting imagery, sharp metaphors and similes, bold comparisons, antitheses, coining of successful maxims, and vivid dramatization characterize his style.

Wendy Porter describes the form of these Kontakia:[10]These are versified sermons set to music, each with a number of metrically identical acrostic stanzas using a common refrain, preceded by a prelude in a different metre.

The metre is not classical but relies on accentuation, with its rhythm established through the syllables in each metrical unit.Today, usually only the first strophe of each kontakion is chanted during the divine services, the full hymn having been replaced by the canon.

His Kontakion of the Nativity is still considered to be his masterpiece, and up until the twelfth century it was sung every year at the imperial banquet on that feast by the joint choirs of Hagia Sophia and of the Church of the Holy Apostles in Constantinople.

[12] The earliest complete manuscripts of his works are dated centuries after his lifetime, akin to those of his successors Andrew of Crete and Kassia.

[13] Karl Krumbacher published in Munich several previously unpublished chants of Romanos and other hymnographers, from manuscripts discovered in the library of the Monastery of St John the Theologian in Patmos.

Krumbacher says of his work: In poetic talent, fire of inspiration, depth of feeling, and elevation of language, he far surpasses all the other melodes.