While success in current and future conflicts will increasingly be predicated by optimisation of high-tech solutions rather than military capabilities based on mass, the application of modern business approaches is of key importance for reforms aiming to adapt security and defence to the new realities. This article presents detailed analysis of ways to adapt the security and defence sector of Ukraine to Euro-Atlantic standards, taking into account Ukraine’s trajectory and growing interaction with the international security systems and the specific context shaped by the external aggression against Ukraine. Based on the analysis of existing legislation and review of theoretical sources, the author concludes that the present archaic, post-Soviet type security and defence sector of Ukraine is not adequate to the future complex challenges. Further, he applies the ecosystem approach to elaborate recommendations for the development of a modern model of national security and defence organisation based on functional integration of the capabilities of all main security and defence actors, emphasising the strategic importance of the integration of Ukraine’s security and defence sector into European and Euro-Atlantic security systems.