Sustainable dairy production will depend on genetic selection for traits linked to environmental efficiency, climate resilience, and animal welfare whilst maintaining economic viability. This chapter provides a comprehensive overview of the scientific, technological and strategic frontiers in dairy cattle phenomics. It outlines the emerging phenotypes gaining attention in the context of sustainable breeding, maps considerations for new technologies in a breeding context, reviews current sensor platforms, and highlights global research efforts and industry applications. It further explores the challenges of integrating phenomic data into breeding programs, from validation and data governance to computational modelling and ethical considerations. Through this lens, phenomics is positioned not simply as a data collection paradigm but as a transformative enabler of next-generation dairy breeding.