Although recent literature on social innovation proclaims its virtue in addressing unmet social needs. Yet little is known about the relationship between phronesis and social innovation. This paper aims to explore how a social entrepreneur uses phronesis in addressing a social problem. Taking case study as qualitative research inquiry, this paper uses the interviews and life account of Dr. Ruth Pfau (Late) on how she incorporated her phronesis in treating patients suffering from leprosy. The empirical evidences collected were analyzed using GIOIA data analysis. The results of the data analysis show that a social entrepreneur employs his/her practical wisdom, experiential knowledge, and value judgment in combating a social issue, and in doing so, uses phronesis in addressing a social problems and creating social innovation.