This study examines the effect of Green Intellectual Capital (GIC) on firm performance at PT Citra Nusantara Gemilang (CNG) Hilir Raya Palembang, a gas distribution company in Indonesia's energy sector. GIC was decomposed into three dimensions: Green Human Capital (GHC), Green Structural Capital (GSC), and Green Relational Capital (GRC). A quantitative associative approach was used, with data collected through a structured questionnaire distributed to 40 employees selected by purposive sampling from a population of 60 employees. Data were analyzed using validity and reliability tests, classical assumption tests, and multiple linear regression with SPSS. All instruments were valid (r-count > r-table of 0.312) and reliable (Cronbach's Alpha > 0.60). The regression equation obtained was Y = 20.105 + 0.261X1 + 0.379X2 + 0.333X3. Partially, GHC had no significant effect on firm performance (t = 1.919; sig = 0.063), whereas GSC (t = 2.909; sig = 0.006) and GRC (t = 3.433; sig = 0.002) had a positive and significant effect. Simultaneously, GHC, GSC, and GRC significantly affected firm performance (F = 60.568; sig = 0.000), explaining 83.5% of its variance (R2 = 0.835). These findings indicate that organizational systems and stakeholder relationships built on sustainability principles are the strongest drivers of firm performance in the energy distribution sector, while individual green competence alone is not yet sufficient. The study offers practical implications for strengthening green structural and relational capital alongside green human resource development to achieve sustainable competitive advantage