Today, many countries believe that Environmental, Social, and Governance (ESG) metrics help investors, companies, and regulatory authorities accurately assess sustainability-related impacts, risks, and opportunities. ESG scores, which also include non-financial information, are not mandatory for companies, but they remain essential for companies that want to maintain their presence in the market. Countries and companies use many ESG measurement metrics. This study analyzes the relationship between the three pillars of ESG scores and firm performance using data for the firms operating in the Borsa İstanbul Sustainability index between 2023 and 2024. The Data Envelopment Analysis (DEA) is employed by using the CRR and BBC models. The findings indicated that according to the BCC model, 17 firms were found to be efficient in 2023, while this number decreased to 13 in 2024. On the other hand, based on the CCR model, 13 firms were identified as efficient in 2023 and only 8 in 2024. The fact that a greater number of firms were found to be efficient under the input-oriented model indicates that, although the firms are technically efficient, they are inefficient in terms of scale. Through both input-oriented and output-oriented DEA analysis, efficient firms with superior profitability, market value, and debt capacity were identified, and firms deemed efficient based on their ESG scores were revealed. This analysis provides insights for firms to develop strategies that may enhance financial performance through improvements in their E, S, and G scores. On the other hand, it also highlights the possibility of improving firm performance without any increase in ESG scores.