Anaerobic digestion (AD) is a promising technology for converting organic waste into renewable energy, but its industrial implementation is often constrained by ammonia inhibition in nitrogen-rich feedstocks, which undermines both process stability and economic viability. Addressing this challenge is crucial for ensuring sustainable, financially resilient waste-to-energy systems. We hypothesized that the strategic addition of bamboo biochar (BBC) could mitigate ammonia stress while promoting a more robust microbial community, thereby enhancing both environmental and economic performance. To test this, batch experiments were conducted to determine optimum BBC dosages, followed by semi-continuous trials using 6.25 g/L BBC over four operational phases (Runs1–4), during which NH₄⁺-N was gradually increased from 2000 to 5000 mg/L. The biochar-amended system maintained stable performance under conditions that caused control reactors to fail, with a maximum 1447 % increase in methane production observed during the 4000 mg/L NH₄⁺-N phase. Mechanistic analysis revealed that BBC acted primarily by enriching syntrophic bacteria and hydrogenotrophic methanogens, enabling a stable syntrophic acetate oxidation pathway. Enhancing microbial resilience through biochar addition directly improves financial stability, a critical factor for industrial adoption. The biochar-added system achieved consistent profits of USD 8.08–16.27/m³ reactor/month, underscoring strong business potential in scalable waste-to-energy systems. Optimizing biochar dosing and evaluating full-scale implementation could further advance globally relevant, economically viable circular bioeconomy solutions.