Our centre-back was dismissed on the half-hour mark for a challenge on Joe Aribo in our 2-1 defeat at Ibrox.
After receiving our appeal, the SFA have deemed his sending off was not a case of wrongful dismissal, which means that Porteous will serve a two-match ban.
He will miss our first two games after the international break when we face Dundee United at home (Saturday 16 October) and Aberdeen away (Saturday 23 October).
