Human Capital Sustainability Mediates Responsible Leadership and Organizational Culture Effects on Sustainable Employee Performance

Objective: This study investigates whether human capital sustainability explains how responsible leadership and organizational culture relate to sustainable employee performance among employees of the Communication Department of Bank Indonesia. Methodology: A quantitative cross-sectional census of all 89 employees was conducted using a five-point Likert questionnaire. The 28-item reflective model was analyzed with partial least squares structural equation modeling in SmartPLS 4. Findings: Responsible leadership did not have a significant direct effect on sustainable employee performance (coefficient = 0.072, p = 0.402), whereas organizational culture had a positive and significant direct effect (coefficient = 0.323, p < 0.001). Responsible leadership (coefficient = 0.397) and organizational culture (coefficient = 0.410) positively predicted human capital sustainability, which positively predicted sustainable employee performance (coefficient = 0.448; all p < 0.001). Human capital sustainability fully mediated responsible leadership (indirect coefficient = 0.178, p = 0.001; VAF = 71.2%) and provided complementary partial mediation for organizational culture (indirect coefficient = 0.183, p = 0.002; VAF = 36.1%). Conclusion: Responsible leadership supports sustainable performance when translated into durable employee capability, whereas organizational culture operates both directly and through human capital sustainability.