Electrocoagulation (EC) of a synthetic ternary dye mixture was investigated using sacrificial iron electrodes. Erionyl Red (ER), Isolan Bordeaux (IB), and Remazol Red (RR) textile dyes were used for preparing the ternary solution. Different operational parameters, including initial dye concentrations, salt amount, current density, EC time, and pH, were analyzed to optimize removal efficiency and energy consumption conditions. After EC treatment, the individual remaining dye concentrations were calculated by applying classical least squares (CLS). The fastest removed dye was RR and the obtained efficiency was the highest as compared to the other two dyes. The energy consumption was also investigated.