Decreasing crude protein (CP) in broiler diets can improve sustainability but may compromise growth performance. Feed additives like coated cysteamine hydrochloride (CSH) and exogenous alkaline protease (EAP) can enhance protein utilization and promote gut health. While CSH modulates metabolism, EAP improves digestibility, but their combined effects in low CP diets remain unclear. This study examines the synergistic impact of CSH and EAP on broiler growth, gut histology, carcass traits, immune response, and nutrient digestibility, aiming to optimize performance while reducing environmental impact. Six-hundred, 1-day-old broiler Ross-308 chicks (male) were allotted to four treatments, each consisting of six replicates of twenty-five birds, in a factorial arrangement using a completely randomized design. The treatments comprised two inclusion levels of coated CSH (0.2 and 0.4 g/kg with or without EAP (0 and 0.2 g/kg) in reduced CP diets. A ten percent reduction in CP from the standard requirements of Ross-308 (20.7% vs. 23% in the starter, 19.35% vs. 21.5% in the grower, and 17.55% vs. 19.5% in the finisher phase) was made in all the dietary treatments. A notable interaction ( ≤ 0.05) between CSH and EAP was detected in body weight gain (BWG), feed conversion ratio (FCR), carcass characteristics, and gut morphology during the whole study duration. Similarly, nutrient digestibility and immune response were also influenced by the combined use of CSH and EAP. The synergistic use of coated CSH at 0.2 g/kg or 0.4 g/kg with EAP in reduced CP broiler diets can enhance performance, intestinal health, carcass characteristics, immune response, and nutrient digestibility. Implications of these findings in commercial feeding practices could substantially improve the efficiency and sustainability of broiler production systems.