In 2004, he was elected [[bishop]] by the local synod of the Antiochian Archdiocese. On [[December 5]], 2004, he was [[consecration of a bishop|consecrated]] at the Patriarchal Cathedral in Damascus, Syria by Patr. [[Ignatius IV (Hazim) of Antioch|Ignatius IV]] and other bishops. He was then [[enthronement|enthroned]] diocesan bishop of the Diocese of Toledo and the Midwest at St. George Cathedral in Toledo, Ohio on [[August 25]], 2005.
After some difficulties regarding the status of the Local Synod in the Antiochian Orthodox Christian Archdiocese of North America, Bp. Mark refused a transfer from his see and requested a release to the Orthodox Church in America, which was officially granted on December 8, 2010. Effective [[January 1]], 2011, Bp. Mark served as Auxiliary to Metropolitan Jonah of Washington, ruling metropolitan of the OCA, with the title "Bishop of Baltimore", and was administer administrator of the OCA [[Diocese of the South (OCA)|Diocese of the South]] and Synodal Liaison for Departments and Commissions of the Orthodox Church in America.
November 13, 2012 he was appointed [[administrator]] of the [[Diocese of Eastern Pennsylvania (OCA)|Diocese of Philadelphia and Eastern Pennsylvania]]. On March, 18, 2014, he was elected by the members of the Holy Synod of Bishops of the Orthodox Church in America to fill the vacant Episcopal See of Philadelphia and Eastern Pennsylvania.