Mealworms (Tenebrio molitor larvae) are increasingly used as alternative protein sources in livestock feed due to their high nutritional value. Recently, interest has expanded to darkling beetle larvae capable of biodegrading polystyrene through gut-associated microbial activity. However, information regarding the safety of incorporating such styrofoam-biodegrading mealworms into poultry diets remains limited. This study evaluated the toxicological and physiological effects of replacing soybean meal with conventional mealworms (CMW) or styrofoam-biodegrading eco-mealworms (EMW) in broiler diets. Seven dietary treatments were tested in a 35-day feeding trial: a control diet without mealworms and diets containing 5%, 10%, or 15% CMW or EMW. Broilers fed diets containing 15% mealworms showed higher average daily feed intake than the control, suggesting improved feed palatability. No apparent toxicological or physiological abnormalities were observed across treatments. Organ weights, hematological indices, serum biochemical parameters, androgen levels, and tissue histopathology were within normal physiological ranges, and no significant differences were detected between CMW and EMW groups. However, as this study represents a pilot-scale evaluation with limited sample size, the statistical power to detect subtle differences may have been constrained. Thus, the absence of significant differences should not be interpreted as definitive evidence of equivalence. Within these limitations, EMW showed a safety profile comparable to CMW at dietary inclusion levels up to 15% for 35 days. Further studies with larger sample sizes are warranted to confirm these findings.