Critical design is born as a form of criticism to traditional, affirmative design, especially in the field of electronic objects. Affirmative design is accused to blindly reinforce the status quo – adhering uncritically to the taste of the time and to the customers desires. Critical design, on the other hand, wishes to challenge it, to shake its users and force them to a wider reflection about human nature, society and its possible alternatives. To this end, it often involves the production of artefacts of a speculative nature, i.e. prototypes or ideas that cannot yet be realized (for technological or ethic reasons) but that have a powerful impact on whoever interacts with them. This idea is rooted in several avant-garde movements active in the 1960s and 1970s mostly in the field of architecture and interior design, such as Italian Radical Design. Andrea Branzi and other experimental designers addressed the role that design played in poetic modes of inhabitation, often with works of a very political and experimental nature. Later, it evolved in critical design theories (in the works of Anthony Dunne and Fiona Raby, for example) and gave birth to several other currents, such as critical play (Mary Flanagan 2009), critical making (Ratto 2008) and design fiction (for a semiotic perspective see Thibault 2018). This paper aims to propose a semiotic interpretation of critical design in order to understand better its working mechanisms and possible cultural role. In particular, objects created by critical design practices will be analysed as signs that encourage atypical chains of interpretants, often escaping the semiosphere and forcing the interpreters to leave a zone of interpretative comfort and follow the interpretants in disturbing and unexplored areas. These objects, then, are capable of casting around them a possible world (Eco 1979) sometimes radically different from ours that, however maintains enough resemblance to work as a parody or an allegory of it, thus encouraging to adopt new perspectives and points of view on our own culture and society.