This study employed an integrated methodology to evaluate the sustainability performance of a biogas-based heating system within a commercial-scale broiler house under real winter conditions in Egypt. A naturally ventilated 24 m² broiler house was equipped with a completely integrated environmental control system (ventilation, lighting, evaporative cooling, and dual heating modes). Poultry litter and farm residues were codigested in optimized proportions with different concentrations of rumen starters to achieve maximum biogas production. The optimal combination (75% poultry litter + 25% residues + 50% starter) was then employed to substitute electric heating in the poultry house with two ventilation time intervals (3 and 5 min). The combined system resolved waste management, renewable energy production, and environmental regulation in parallel. Maximum daily biogas yield was 25.6 L/day with up to 85.6% methane content providing thermal efficiencies of 850 MJ/day. Biogas heating provided thermal stability and reduced temperature–humidity index scores compared to electric heating, especially with 5-min ventilation, enhancing bird welfare. Broilers reached 10% higher final body weight (2.4 kg) and 25% improved feed conversion ratio (1.2) compared to electric heating. Total and specific energy utilization decreased to 1.4 kWh and 0.6 kWh/kg, respectively, while production cost decreased by up to 30% and the net profit increased to 0.80 USD/kg. By on-site valorization of waste, renewable energy supply, and climate optimization, this study demonstrates a novel, field-scale strategy to sustainable poultry production. The findings affirm that biogas technology could consistently counteract dependence on fossil fuels, lower the expense, and increase productivity, presenting an expandable pathway toward circular and climate-resilient livestock farming.