This dissertation studies how firms transform to meet the growing market for sustainable businesses. Stakeholder pressures, technological innovations, and economic incentives have enabled ample market opportunities for sustainable businesses, yet we know little about how firms go about seizing such opportunities and what barriers they face during the transformation. Both questions are particularly pressing among incumbent firms with legacy businesses in traditional markets: despite foreseeable challenges they may face if were to break away from their existing operations, these firms are the ones that could benefit the most from--and contribute the most to--a vibrant market for sustainable businesses. In addition to a theoretical chapter (Chapter 2) examining how categorical barriers take shape in multiple dimensions to affect firms, I develop two empirical chapters to understand the process towards (Chapter 3) and the outcomes of (Chapter 4) corporate transformation into sustainable businesses. Chapter 3, "Labor-Market Barriers and Corporate Sustainability: Evidence from Millions of Online Job Posts 2007-2019", examines how brown-industry firms hire sustainability-related talent, showing the systematic barriers faced by these firms in acquiring talent to make this transition. Chapter 4, "Product-Market Barriers and Corporate Sustainability: Evidence from the US LED Lightbulb Market 2006-2015", examines how firm expansion in sustainable product markets affects consumer evaluations on incumbent products. Both empirical chapters offer organizational and strategic implications for firms to navigate the growing market for sustainable businesses.