A ranar 15 ga Yuli, 668, mai ba da shawara ya kashe Contans II a cikin wankansa, a cewar Theophilus na Edessa, da guga.Ɗansa Constantine ya gaje shi a matsayin Constantine IV.Sabon sarki ya murkushe wani ɗan kwata-kwata a Sicily da Mezezius ya yi.Constantine IV shi ne Sarkin Rumawa daga shekara ta 668 zuwa 685. A zamanin mulkinsa ya ga babban bincike na farko zuwa kusan shekaru 50 na fadada Musulunci ba tare da katsewa ba, yayin da kiransa na Majalisar Ecumenical ta shida ya kawo karshen takaddamar Tauhidi a Daular Rumawa;saboda wannan, ana girmama shi a matsayin waliyyi a Cocin Orthodox na Gabas, tare da ranar idinsa a ranar 3 ga Satumba. Ya yi nasarar kare Konstantinoful daga Larabawa.