Knowledge integration is a major challenge of interdisciplinary research. Substantially different stocks of knowledge based on different scientific backgrounds, uses of language, methodologies, and epistemologies must be integrated into the research process. Addressing this challenge, this paper exemplifies the process of interdisciplinary knowledge integration drawing on the example of the junior research group DynaMo—Mobility-Energy Dynamics in Urban Areas that deals with the sustainable transformation of urban mobility systems. This paper shows how we apply the boundary object concept in combination with the method of Constellation Analysis as vehicles for interdisciplinary knowledge integration. By innovatively combining the boundary object concept with Constellation Analysis we a) suggest a self-reflective tool for structuring the process of knowledge integration and b) further operationalize the boundary object with the help of core concepts. The approach is illustrated with the boundary object sustainable transformation of urban passenger mobility used by DynaMo. In doing so, the paper aims to add an instrument to the toolkit of inter- and transdisciplinary research and offers practical knowledge for its application.