Garrido was hired by the 10-time Tunisian league champions in November with a mandate of challenging Esperance de Tunis for league glory.
With a sterling reputation as a two-time CAF Confederations Cup winner with Al Ahly and Raja Casablanca, as well as LaLiga experience with Villarreal and Real Betis - Garrido brought a wave of fresh optimism.
But his stint with Etoile has come to an abrupt end after just 13 games in charge despite his impressive Champions League exploits.
A 1-0 victory over record-eight time champions Ahly in their final Group B encounter was enough to secure first place heading into their quarter-final tie against Wydad Casablanca at the end of the month.
However, their 1-1 draw with CS Sfaxien left them 17 points adrift from Esperance after 13 games in the 14-team Tunisia top-flight.
A run of one win in five was enough for the club's hierarchy to pull the plug on the Spanish tactician with a reported compensation package of $890,000.
L'étoile travel to Wydad for the last-eight Champions League tie on Saturday, 29 February at the Stade Mohamed V before their return leg in Rades on 7 March.