The centre-back served an automatic ban in the 3-1 first-leg victory in the Champions League second qualifying round after being sent off against Alashkert in the previous round.
Croatian defender Simunovic caught Brazilian forward Jefferson with a high boot in the early stages of the second leg of the Champions League first qualifying round tie with the Armenian champions.
UEFA’s control, ethics and disciplinary body (CEDB) has now decided his challenge warranted further punishment.
A UEFA statement read: “The CEDB has decided to suspend the Celtic player Jozo Simunovic for two UEFA competition matches.
“The player has already served one match and will therefore be suspended for the next match for which he would be otherwise eligible.”
Simunovic’s absence leaves Celtic rather light in defence, with Dedryck Boyata and Mikael Lustig still absent after their World Cup exploits, and German centre half Marvin Compper out injured.
Kristoffer Ajer and Jack Hendry will likely start in the middle with Cristian Gamboa and Kieran Tierney in the full back slots.
However, that would mean Brendan Rodgers would have young duo Calvin Miller and Anthony Ralston as his only back-up defenders.