Probability signifies a mainstream strand in mathematics curricula. Nonetheless, many curricular documents prepared for teachers might not offer enough support. In such a situation, a further reflection on teachers' professional knowledge for teaching probability is demanded; especially, from the perspective of probabilistic reasoning (PoPR) that is consistent with the need to pave the way for theories about mathematics education and cognitive psychology to consolidate achievements from each other. Accordingly, this study aims at conceptualizing mathematics teachers' professional knowledge forteaching probability from the PoPR. The initial step towards this conceptualization started by inferring the fundamental entities of teachers' professionalism through utilizing the mathematical knowledge for teaching model. Following this, three significant propositions were acknowledged. As a result, a conceptual framework was proposed, and a practical example was described. Such a description symbolizes a transition from emphasizing content knowledge towards highlighting teachers' process knowledge, which may impact the development of probability education research.