Environmental, Social, and Governance (ESG) investing has rapidly evolved now into a critical component of global investment strategies, despite its roots in Socially Responsible Investing (SRI) dating back over two centuries. ESG gained prominence in the 1980s and was formally recognized in 2006 by the United Nations Principles for Responsible Investment (PRI), aligning it with global frameworks such as the Sustainable Development Goals (SDGs) and the Paris Climate Agreement. This paper reviews the evolution of the ESG investment ecosystem, examining key contributors, including regulators, fund managers, corporations, and rating agencies, and their roles in promoting ESG adoption. Recent regulatory initiatives, such as the U.S. SEC's ESG disclosure rules, the European Commission's Sustainable Finance Disclosure Regulation (SFDR), and India’s Business Responsibility and Sustainability Reporting (BRSR) framework, represent significant efforts to streamline ESG reporting and reduce greenwashing. However, the lack of harmonized global standards and inconsistencies in ESG reporting and scoring methods remain critical challenges. This study analyses the performance of leading ESG funds in the U.S. and India over a four-year period, benchmarking their returns against major market indices. Additionally, it explores the correlations between ESG fund performance and market benchmarks, as well as the similarities in stock holdings between ESG and non-ESG funds. The findings reveal that while ESG funds perform comparably to or below traditional indices, significant gaps persist in defining ESG criteria and measuring performance effectively. The paper concludes with a call for global harmonization of ESG reporting standards and scoring methodologies to ensure consistency, transparency, and investor confidence. As ESG investing is poised for substantial growth, establishing clear definitions and robust frameworks will be essential to unlocking its potential as a transformative force in sustainable finance.