Introduction Intensive livestock farming has sparked public debate, highlighting the need for sustainable livestock production. One effective strategy to improve both environmental sustainability and meat quality is the inclusion of agro-industrial byproducts in pig diets. This study aimed to investigate the effects of dietary inclusion of hazelnut skin (HS) or its green polyphenolic extract (HSE) on growth performance, carcass traits, and meat quality in heavy pigs. Methods Seventy-two pigs were allotted to three dietary treatments ( n = 24 each): a control group (C) fed a standard diet, and two experimental groups receiving the same diet, including either 0.6% HS replacing 0.6% of wheat bran (HSD) or adding 0.1% HSE (HSED). After growth performance assessment, 36 subjects, balanced by gender and treatment, were slaughtered for carcass and meat quality evaluations. Results No differences were observed in growth performance or carcass yield, indicating all diets met nutritional needs. However, HSE supplementation increased thigh yield ( p < 0.01). Overall, meat quality characteristics did not differ among treatments; however, HS inclusion showed positive trends in oxidative stability during cooking, n-3 polyunsaturated fatty acid content, and the n-6/n-3 ratio. HSE supplementation decreased cooking loss, giving it better water-holding capacity. The treated groups showed a reduction in cholesterol content in the meat of 7.56 and 12.10% in the HSD and HSED groups, respectively. Conclusion Overall, the modest yet positive effects, combined with the absence of negative influences on growth performance, carcass traits, and meat quality, indicate that HS and HSE supplementation could offer commercial and environmental benefits in sustainable livestock systems.