The relevance of gender diversity and environmental, social, and governance (ESG) performance reporting is critical to corporate sustainability. This study aims to analyze the impact of gender diversity on ESG performance reporting and analyze the mediating effect of the workforce and sustainability reports, considering that these variables are crucial for ESG performance reporting. To achieve the objective, an empirical analysis was conducted with 207 European-listed companies belonging to the healthcare sector for the economic years 2017–2021. Our results prove that board gender diversity influences ESG performance reporting. In addition, this research shows that the workforce and sustainability reports have a positive impact on ESG performance reporting. This study does not show that the workforce and sustainability reports act as mediating variables in the relationship between gender diversity and ESG information transparency, but its inclusiveness has a significant impact on ESG performance reporting. Our results are useful for companies, investors, governments, and organizations in developing sustainability reporting standards.