The boy-king succeeded Smenkhkare to the throne and was crowned king at Memphis at the age of nine. He had no close living relatives, since his possible mother Kiya and stepmother Nefertiti were both deceased, so he was under the care of Ay, a senior civil servant who may have been Nefertiti's father, and Horemheb, the commander-in-chief of the army. Ay and Horemheb served as Tutankaten's primary advisors, along with Nakhtmin, another military officer, and Maya, treasurer and overseer of the royal cemetery, and would each succeed to the throne one after the other following Tutankhaten's untimely death. 

      Tutankhaten's first action as king was to re-establish the old religion that Akhenaten had replaced with aten-worship. He moved the administrative center from Akhetaten back to Memphis, re-established Thebes as the religious center of Egypt and reopened temples to Amun that Akhenaten had closed. To emphasize the return to the worship of Amun, Tutankhaten and his wife Ankhesenpaaten changed their names to Tutankhamen and Ankhesenpaamun. The reign of Tutankhamen was truly a period of religious restoration.  In order to ensure legitimacy during his reign, Tutankhamen stressed an association with Akhenaten's predecessor, Amenhetep III. 

      Tutankhamen undertook building projects at Luxor, where there are relief scenes of the Festival of Opet on the processional colonnade, and Karnak. His construction at Karnak is recorded on the "Restoration Stelae." Many of his monuments were usurped  by later rulers, especially Horemheb. Little is known of Tutankhamen's foreign policy: military campaigns in Palestine/Syria and Nubia are recorded, but it is doubtful that the king actually participated in the skirmishes. 

      Tutankhamen died during the 9th year of his reign at the age of 17. A small bone fragment within his skull is visible in x-rays, and it is possible that the king was murdered. He was buried with extensive treasures in an adapted private tomb in the Valley of the Kings,  probably because the construction of his intended tomb in the West Valley of the Theban Necropolis had scarcely just begun. The mummy, innermost coffin, and sarcophagus of Tutankhamen are in his tomb but the other contents are on display in the Cairo Museum.