Daphnopates first appears in the sources in the mid-920s, having apparently entered the service of the imperial court shortly before. In 924/5, Daphnopates composed three replies of Emperor Romanos I Lekapenos (r. 920–944), to letters by Tsar Symeon I of Bulgaria. In these letters, Romanos I criticized Symeon as rapacious and warlike, while trying to move him to accept a peace bringing an end to the long war between Byzantium and Bulgaria. Ten more letters to rulers and ecclesiastical leaders in Bulgaria and Armenia, written on behalf of Romanos I in the period 925–933, survive, indicating that Daphnopates probably held the post of head of the imperial chancery ("protasekretis"). A number of modern scholars—Ivan Dujčev, R. J. H. Jenkins, and Patricia Karlin-Hayter—have suggested that Daphnopates was the author of the anonymous speech celebrating the conclusion of peace with Bulgaria in 927 () and the concurrent marriage of Tsar Peter, the son and successor of Symeon, with Maria Lekapene, the granddaughter of Romanos I. The Greek historian Alkmini Stavridou-Zafraka however rejected this identification.