Conjugated cricket protein with fructooligosaccharide (FOS), called CPF, is a new alternative protein ingredient with great potential for food industry applications. This study aimed to investigate the effect of CPF as a partial substitute for rennet casein on the composition, appearance, color, antioxidant activities, sensory characteristics, and functional characteristics of imitated mozzarella cheese. The effect of CPF on vitamin D retention of cheese after processing and 28 subsequent days of storage was also studied. Incorporation of CPF by 10-40 g/100g resulted in significantly increased FOS as prebiotic fibers by about 0.1-4.2 g/100g in imitation mozzarella cheese, but slightly decreased the protein content and shifted color balance darker, with more yellow and red. The addition of CPF reduced hardness, cohesiveness, springiness, and stretchability (25.0-3.6 cm) but increased meltability, adhesiveness, and free oil release (2.0-9.3 cm) of cheeses. In addition, CPF enhanced vitamin D stability in the cheese matrix by about 3 times after heat treatment and 2.8 times after 28 days of storage (4 °C) when compared to the control. It is concluded that adding 10-20 g/100g CPF in imitation cheese improved vitamin D stability and provided acceptable sensory scores for consumers (like moderately, 7.1-7.3).