Pollution caused by nonrenewable plastics has driven the use of natural polymers. Similarly, the disposal of food waste still harms the environment. Considering both aspects, this study aimed to evaluate the effect of incorporating orange by-product powder (OBP) as a reinforcing material into sodium alginate films with glycerol. Sodium alginate-based films were produced using glycerol and various concentrations of OBP. The films were characterized in terms of thickness, color, water content, mechanical properties, light transmission, transparency, X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), contact angle, solubility, swelling, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The addition of OBP significantly (p < 0.05) reduced the water content of the film from 37.75% ± 5.80a (0-OBP) to 24.49% ± 1.47b (45-OBP). The higher the concentration of OBP, the higher the tensile strength of the films, from 7.99 MPa ± 0.91a (0-OBP) to 18 MPa ± 1.38d (45-OBP), and the higher the hydrophobicity, from 57.60° ± 0.41a (0-OBP) to 70.34° ± 0.98c (45-OBP). From TGA and XRD analyses, it was observed that the incorporation of OBP resulted in less crystalline and more thermally resistant materials. Therefore, this study shows that OBP is a promising reinforcing component for sodium alginate films.