ABSTRACT This study aimed to determine the optimal proportion of cottonseed cake (CSC) as an additive in sorghum silage to improve its chemical composition, fermentative profile, microbial populations, losses, dry matter recovery, and aerobic stability. Five treatments were evaluated, varying the inclusion of CSC at ensiling (0, 50, 100, 200, and 200 g kg−1 on fresh matter basis). The results showed that the inclusion of CSC significantly increased the content of dry matter, crude protein, and ether extract in the silages. Water-soluble carbohydrates, buffering capacity, and ammoniacal nitrogen exhibited a linear decrease with increasing CSC inclusion. The populations of lactic acid bacteria and moulds showed a quadratic response to CSC inclusion. The yeast population was completely inhibited with a minimum inclusion of 200 g kg−1 CSC. Aerobic stability and dry matter recovery showed a linear increase with CSC inclusion. These findings indicate that adding CSC to sorghum silage enhances its nutritive value, fermentative profile, dry matter recovery, and effectively inhibits yeast growth, which is recommended to include 200 g kg−1 of CSC for good cost-effectiveness.