This study examines the central role of Japanese mothers in sustaining family life within tanshin funin households, a long-standing corporate practice where employees are relocated abroad without their families. Emerging from Japan’s post-war employment system of lifetime employment and corporate transfers, tanshin funin has created a unique form of transnational family life that remains underexplored. While earlier research highlighted stress and psychological strain, this study focuses on mothers’ agency and the strategies they develop to maintain cohesion across borders. Based on semi-structured interviews with ten mothers in the Tokyo metropolitan area, the analysis identifies three interlinked strategies: cultivating emotional independence, assuming intensified responsibility for children, and using digital technologies to sustain transnational caregiving. These practices not only ensured stability for children at critical educational stages but also enabled fathers to remain connected despite distance. Mothers acted as linchpins, transforming separation into a workable arrangement that preserved both family life and corporate demands. By situating these experiences within Japan’s ageing society and broader debates on migration and transnational care, this study underscores the invisible, gendered labour that underpins corporate mobility and family resilience. It reframes tanshin funin as a transnational phenomenon and highlights the adaptability of women who negotiate caregiving for both children and ageing parents while sustaining ties across borders.