Designing opportunities for play in the built environment is crucial to support children’s health and development. A growing research focus on child-friendly environments has evidenced a shift toward creating spaces and buildings that take children’s needs seriously and work with children as capable experts and active collaborators. Yet, limited attention has focused on how different scholars conceptualise and operationalise research on understanding and designing opportunities for play in the built environment. This paper reports on the findings of a scoping review of peer-reviewed empirical literature (51 publications) from 1994 to 2019. We examine the trends and trajectories in conceptualising and operationalising research on understanding and designing opportunities for play and map the landscape of scholarship through four analytical categories: (1) who is involved in play and research studies, (2) what is the thematic focus and in what ways is play investigated in reviewed studies, (3) how are opportunities for play explored methodologically, including how/when are children involved in research, and (4) where do play and research studies occur. Our findings reveal three key challenges for future work: (i) greater appreciation and engagement with children’s diversity; (ii) ensuring a nuanced understanding of play as a spectrum of opportunities and types; and (iii) exploring the democratic context of play between formal and informal play spaces to bolster children’s right to the city. We invite researchers, practitioners, and policy makers to work closely with children, engage with their diversity and explore interdisciplinary and interprofessional avenues to promote opportunities for play across the built environment.