Design processes in engineering are rapidly evolving from empirical, experience-based approaches to computer-centred methodologies grounded in numerical simulation and data-driven strategies. Within this transformation, topology optimization has become a key enabler, advancing structural, multi-physical and multidisciplinary design, including solid mechanics, acoustics, fluid dynamics, and fluid–structure interaction problems. These methods drive innovation by revealing novel design concepts, enhancing performance, and improving material efficiency. Recent progress in advanced manufacturing, for example additive manufacturing, has further expanded the potential of topology optimization, enabling the realization of complex, high-performance structures previously beyond reach. While applications in the automotive and aerospace industries are well established, adoption is rapidly growing across a wide range of engineering fields. This mini-symposium will primarily address recent methodological advances in topology optimization - spanning solids, fluids, and fluid–structure interaction - while also presenting illustrative applications that demonstrate its expanding impact in engineering practice.