Abstract The study examined the cost implications of green innovation practices on firm value in the Nigerian manufacturing industry. This study used an ex-post facto research design to investigate the effects of green product and green process disclosures on firm value. Data from ten manufacturing companies listed on the Nigerian Exchange Group between 2017 and 2021 were gathered through secondary sources. A panel regression analysis was used to investigate the relationship between green innovation variables (green product disclosure and green process disclosure) and firm value, while adjusting for firm size. The findings found that green product disclosure had a negative and insignificant effect on firm value. On the other hand, green process disclosure was discovered to have a negative and significant impact on firm value. Furthermore, firm size was discovered to have a negative and non-significant effect on firm value. Based on the findings, it was recommended amongst others that policymakers and regulatory authorities should enforce the compliance requirements and constraints associated with green disclosures as this will aid firms to achieve sustainability goals thus avoid unnecessary costs. Key Words: Green innovation disclosure, green product disclosure, green process disclosure, firm size and firm value