This paper suggests that design ethics can be enriched by considering ethics beyond the traditional approaches of deontology, teleology, and virtue ethics. Design practice and design ethics literature tend to frame ethics in design according to these approaches. The paper argues that a fundamental and concrete ethical understanding of design ethics can also be found in Sartrean Existentialism, a philosophy centered on the individual and his/her absolute freedom. Through the analysis of four core concepts of Sartrean Existentialism that define a specific ethics, the paper illustrates why such philosophical approach is relevant to design ethics. The paper also shows how Sartrean Existentialism and its ethics apply to critical issues of professional practice in design such as professional engagement and design decision-making. The paper finally argues that Sartre’s philosophy and ethics is a perspective that offers the designer in design practice a solid ground to engage his/her ethical dilemma.