Strategic communication of organizations has numerous points of contact with sustainability issues. In addition to its mediating role, which refers to the reporting on how an organization shows commitment to sustainability, strategic communication can also be assigned a promoter role for a sustainable transformation both within and beyond the organization. Another aspect to consider is how strategic communication can itself be sustainable. In this contribution, we introduce the concept of sustainable strategic communication, which combines ideas regarding how strategic communication itself is sustainable while promoting sustainable transformation. We first characterized sustainable strategic communication by proposing a comprehensive heuristic that systematizes the various connections of strategic communication to sustainability issues. This heuristic was then discussed with 14 experts in the field in guided interviews and subsequently developed further in a workshop with 21 communication professionals. The results of both steps are outlined in this paper. Through this multilevel characterization of sustainable strategic communication, we put forward a concept that may guide professionals and researchers of strategic communication through the Great Transformation towards Sustainability.