XII Apostoli) on 11 February 1965 when he was raised to the rank of cardinal bishop pursuant to Pope Paul VI's motu propio Ad Purpuratorum Patrum issued on that day which decreed that Eastern Patriarchs elevated to the College of Cardinals would be cardinal bishops, ranked after the suburbicarian cardinal-bishops, and maintain their patriarchal sees and not receive any assignment to associate them with the Diocese of Rome.
On February 11, 1965, Cardinal Apostoli was made a cardinal bishop by Pope Paul VI's decree "Ad Purpuratorum Patrum." This decree established that Eastern Patriarchs elevated to the College of Cardinals would be cardinal bishops, ranking after suburbicarian cardinal-bishops and retaining their patriarchal sees while not being assigned to associate them with the Diocese of Rome.