This paper investigated the impact of Green Human Resource Management (GHRM) practices on business sustainability in selected SMEs in Port Harcourt, Nigeria. A descriptive survey design was used to investigate a population of 697 employees of selected SMEs in Port Harcourt and a sample size of 254 was derived from the population using Taro Yamane’s formula. Well-structured questionnaires were designed and used to obtain responses from the respondents. Data obtained was analyzed through regression analysis using SPSS version 21.0. Findings of the study indicated a significant positive correlation between green human resources and sustainability, revealing that companies implementing green policies enjoyed enhanced employee engagement, reduced costs, and better environmental compliance. Additionally, training in environmental practices and promoting sustainable behavior were necessary factors for these positive outcomes. Hence, there is a need for SME managers to incorporate green HR strategies to promote environmentally responsible and economically viable businesses in Nigeria’s evolving market.