This study investigates the market reactions to firms’ inclusion in the Environmental, Social, and Governance (ESG) index. Specifically, we investigate whether firms that adopt the Task Force on Climate-Related Financial Disclosures (TCFD) framework experience variations in abnormal returns. Analyzing a sample of 71 companies from the FTSE ESG index in Taiwan between 2019 and 2021, we discern a positive market reaction to compa-nies incorporated into the ESG index. Additionally, companies that embrace the TCFD framework demonstrate elevated abnormal returns. Contrary to prior research indicating a negative market impression of Asian companies with superior sustainability achievements, our study implies a growing favorable perception by Asian investors toward companies actively participating in sustainability initiatives.