Sustainable entrepreneurship merges the pursuit of business opportunities with a commitment to environmental stewardship and social well-being. This chapter explores the behavioral dimensions underpinning sustainable entrepreneurship—the motivations, decisions, and actions of entrepreneurs who aim to achieve the “triple bottom line” of people, planet, and profit. We begin by defining key concepts, including sustainable development and sustainable entrepreneurship, and review foundational theories such as the triple bottom line framework and stakeholder theory. We then examine the behaviors and mindset of sustainable entrepreneurs, drawing on evidence from research and real-world examples. This includes an analysis of how personal values, cognitive factors, and global trends (e.g., the rise of AI and climate innovation) influence entrepreneurial intentions and ventures that prioritize sustainability. Further sections discuss debates and challenges, from balancing profit with purpose to addressing greenwashing and scaling impacts. Practical strategies and tools for sustainable entrepreneurship are highlighted, and a global perspective is taken with examples from different contexts. A case study of Patagonia, the outdoor apparel company, illustrates the chapter’s themes in practice. The chapter concludes with key takeaways and reflection questions, reinforcing the learning objectives and encouraging deeper consideration of the role of behavior in driving sustainable entrepreneurial success.