Midfielder Guerbert was left with a fractured tibia and fibula in his right leg, together with a dislocated ankle, following a rash challenge from Zouma in Saturday's Ligue 1 match at Stade Auguste-Bonal.
Zouma was sent off, but now faces a lengthy spell on the sidelines after the Professional Football League (LFP) opted to dole out an extended suspension as part of their 'zero-tolerance' approach to tackles that cause players to sustain serious injuries.
Nice's Valentin Eysseric was given an 11-match ban last season for a leg-breaking challenge on Saint-Etienne's Jeremy Clement.
Zouma's ban will be served across all domestic competitions and means he will not play again until 2014.
The news comes as a significant blow to Saint-Etienne, as the France Under-21 international had featured in all but one of their 12 league games to date.
