Dedia was Chief of Draftsmen-Painters in Karnak, serving the Vizier, Paser, who was engaged in directing the construction and decoration of buildings commissioned by King Seti I. He supervised the decoration of the hypostyle hall at Karnak, one of the masterpieces of New Kingdom architecture. Set's son, Ramesses, who would eventually succeed Seti as king, was also closely involved, and Dedia would have worked to the prince's instructions likewise.

He was also responsible for the restoration of the monuments of earlier kings and queens of Egypt, including Queen Ahmose Nefertiry, Amenhotep I and Thutmose III. A palette has been found which still retains colors and which may have belonged to Dedia.

Dedia came from a long line of professional artists; he was of the sixth generation of his family to work at Thebes. The family originally cam from Syria or Canaan.