This paper examined changes in environmental reporting following the introduction of the New Zealand Stock Exchange (NZX) Corporate Governance Code, which recommends reporting of environmental, social, and governance (ESG) information. The environmental disclosures of the top 50 NZX companies from 2016–2020 were analysed, comparing reporting pre-(2016–2017) and post-(2018–2020) introduction of the ESG guidance. Univariate and multivariate statistical analyses were used to examine changes in environmental reporting over these periods. The ESG guidance significantly improved environmental reporting, but not all companies disclosed information, indicating the need for stronger regulations. The study examined the trend in environmental disclosures, before and after implementation of the ESG guidance note, in the context of New Zealand's transition to mandatory climate reporting for listed companies. The study provides evidence of listed companies responding to listing requirements to provide greater transparency to capital markets regarding the environmental impact of their operations on the environment. The most frequently reported environmental disclosure was greenhouse gas emissions, widely recognised as a primary contributor to climate change.

Keywords: Environmental Reporting, ESG Guidance Note, Greenhouse Gas Emissions, Legitimacy Theory