Corporate sustainability is a key factor in facing intense competition in both global and local business environments. The implementation of Good Corporate Governance (GCG) principles is believed to support the achievement of such sustainability. This study aims to analyze financial performance, the application of GCG principles, and their impact on corporate sustainability, using PT. EFLYID, a laying hen farming company in South Sulawesi, as a case study. Because PT. EFLYID is the first laying hen farm company in South Sulawesi Province to obtain a Veterinary Control Number (NKV) certificate and implement the principles of Good Corporate Governance in its operational activities. The research was conducted from September to November 2024 using a mixed-methods approach. Data were collected through observations and interviews, then analyzed using simple linear regression with SPSS 25. The results show that PT. EFLYID has healthy financial performance and sustainable profitability over one period, with sales and revenue consistently above the Break-Even Point (BEP). The application of GCG principles is reflected in transparency of information, a clear organizational structure, and commitment to regulations and social responsibility. The effective implementation of GCG has a significant impact on corporate sustainability, with a strong relationship between good financial performance, effective GCG implementation, and commitment to sustainability.