Abstract The aim of this paper is to provide an account of extension that strictly follows from the organizational theory of autonomous systems, further developing recent enactive accounts of extension and incorporation. We examine Moreno and Mossio’s definition of an autonomous system, developed in Biological Autonomy . Then, we argue that their definition provides two different ways an autonomous system can extend its autonomy to external entities (extension by constraint surrogate and extension by constraint composition), together with a criterion for each case of extension. We also consider that each case can be characterized by transformations of the autonomous system’s viability space, normative field and topological unity. We discuss the consequences of our account for the recent enactive views on incorporation and extension, arguing that the notion of ‘extension’ does not necessarily require functionalism and that it can be usefully adopted by enactivism. Finally, we show that a productive tension is created between the extension cases developed here and the enactive accounts of incorporation.