The preconception period is a key public health and clinical opportunity for obesity prevention. This paper describes the development of international preconception priorities to guide research and translation activities for maternal obesity prevention and improve clinical pregnancy outcomes. Stakeholders of international standing in preconception and pregnancy health formed the multidisciplinary Health in Preconception, Pregnancy, and Postpartum (HiPPP) Global Alliance. The Alliance undertook a priority setting process including three rounds of priority ranking and facilitated group discussion using Modified Delphi and Nominal Group Techniques to determine key research areas. Initial priority areas were based on a systematic review of international and national clinical practice guidelines, World Health Organization recommendations on preconception and pregnancy care, and consumer and expert input from HiPPP members. Five preconception research priorities and four overarching principles were identified. The priorities were: healthy diet and nutrition; weight management; physical activity; planned pregnancy; and physical, mental and psychosocial health. The principles were: operating in the context of broader preconception/antenatal priorities; social determinants; family health; and cultural considerations. These priorities provide a road map to progress research and translation activities in preconception health with future efforts required to advance evidence-translation and implementation to impact clinical outcomes.