This chapter attempts to highlight the importance of ethics and its principles in entrepreneurship and sustainable business activities. To this end, the first section of the present chapter compares ethics in classical entrepreneurial theories with ethics in new or sustainable entrepreneurial theories. In the next step, an attempt was made to examine the most important indicators of entrepreneurial ethics. Also, in the third step of this chapter, social entrepreneurship was proposed and justified as a suitable tool and approach for sustainable and ethical entrepreneurship. In the fourth phase, an attempt was made to examine and discuss greenwashing as an unethical competitive strategy and to identify and discuss its negative consequences in both the short and long term. Finally, practical strategies for developing sustainable entrepreneurial ethics were presented. Additionally, a case study was presented on the topic of greenwashing and consumer perceptions of organic food products among Iranian consumers.