Meat preservation is necessary to prevent harmful changes caused by microbiological, chemical, and physical processes in order, among other things, to extend storage life. In this study, we investigated how the duration (4, 8, 12, and 24 h) and temperature (50 °C, 55 °C, 60 °C) of SV (sous-vide) treatment for horse meat influence the sensory properties and quality of m. longissimus thoracis specimens. The SV temperature and time of heat treatment demonstrated notable enhancements of most texture parameters. Increasing the duration of heat treatment from 4 h to 8, 12, and 24 h at all applied temperature values resulted in an improvement in the shear force, hardness, springiness, gumminess, and chewiness of horse meat (however, the differences were not statistically significant in every case). Increasing the duration of heat treatment from 4 to 24 h, but only at a temperature of 60 °C, improved the scent (intensity and desirability) and flavor desirability. Multiple regression analysis showed that many texture parameters could be effectively described by the cooking time and process temperature. The most accurate representation of the empirical data (R2 > 0.903) was attained for adhesiveness, springiness, gumminess, and chewiness, which exhibited the highest coefficients of determination.