This chapter provides insight into how highly successful mid-sized companies with global market leadership in niche segments—so-called hidden champions—integrate sustainability principles into their strategic decision-making. Based on comparative case studies from a diverse range of countries across Central and Eastern Europe, Asia, and Africa, the analysis provides similar patterns, differences and peculiarities in the depth and form of sustainability implementation. While many hidden champions demonstrate strong alignment between environmental, social, and innovation strategies, others remain at an early stage of integration. Key drivers include regulatory pressures (e.g. Environmental, Social, Governance (ESG)and The Corporate Sustainability Reporting Directive (CSRD) frameworks), innovation capacity, family ownership values, industrial factors, and geopolitical developments. The chapter highlights that sustainability is evolving from a peripheral concern into a core source of competitive advantage and it is becoming an integral part of hidden champion strategic framework. By identifying three distinct clusters of integration (high, medium, low), the study offers original empirical evidence from under-researched regions and provides inspirational practices how to support sustainable transformation among mid-sized companies globally.