Abstract: Orange residues are an excellent carbon and energy source to obtain high added value compounds through bioprocessing, such as single-cell protein (SCP). This study aims to evaluate the orange peel as the only carbon and energy source for the growth of Candida utilis and evaluate and optimize the SCP production by submerged fermentation. A comparison of three fermentation media was made using different mineral salts and orange peel as the sole carbon source (10%), where each medium was inoculated with 1 × 106 cells of C. utilis at the same conditions of 150 rpm at 30 °C for 96 h. Optimization was carried out with a Box Bhenken 33 design. The results showed that orange peel is an excellent source of nutrients, especially in total carbohydrates and minerals such as calcium and potassium. The fermentation results showed greater yeast growth when using Medium 1, obtaining 13.42 g L-1 of biomass. In addition, Candida utilis has the higher consumption of total sugars and reducing sugars in the medium 1 with 81 and 89%, respectively. Optimization of the medium and fermentation conditions was achieved, obtaining 15.71 g L-1 and 6.22% of biomass and total protein, respectively. Therefore, the orange peel is an agro-industrial waste with the potential to be used as a carbon source for the growth of C. utilis.