The equilibrium solubility of sulfamerazine (SMR) in neat ethylene glycol (EG) and nineteen {(EG) (1) + water (2)} mixtures is reported at temperatures from (278.15 to 318.15) K. Mole fraction solubility of SMR (x3) increases with temperature arising and also increases with the EG proportion increasing. It varies from 1.71 × 10−5 in neat water to 7.78 × 10−4 in neat EG at 298.15 K. Solubility behavior was correlated by the extended log-linear model of Yalkowsky, the Jouyban-Acree model, and Jouyban-Acree-van’t Hoff model and the obtained mean percentage deviations are 80.1%, 6.7% and 6.6%, respectively. From the variation of solubility with temperature, the apparent thermodynamic analysis of dissolution and mixing processes was performed in all the mixtures and neat solvents. From inverse Kirkwood-Buff integrals (IKBI) calculations is observed that SMR exhibits low negative preferential solvation parameters by EG in water-rich mixtures. Otherwise, SMR is preferentially solvated by EG in the interval (0.24 < x1 < 1.00).