For children living in one of the 30 megacities around the world, green spaces may be far away or tokenistic, with growing accounts of youth exhibiting a variety of nature deficit disorders. Amidst increasing pressure for more high-density metropolitan areas (HDMAs), international advocacy agencies are calling for policy makers and service providers to ensure good quality urban green spaces (UGSs) for all children. Furthermore, these green spaces need to be purposefully designed to cater to children’s needs, which continue to evolve amidst extreme weather such as heat waves. Recently, pandemics have placed additional constraints on how far children can travel and their time spent outdoors, making the quality of this experience for children even more important. This systematic literature review explored the roles of HDMA-UGSs for children during pandemics. From 551 studies retrieved and curated using the PRISMA methodology, 40 papers were subsequently thematically analysed. Four roles were synthesised for HDMA-UGSs in supporting children’s experiences during pandemics, which also benefit children during ‘normal’ day-to-day life’: (1) sustaining growth and development, (2) bridging social stratifications, (3) encouraging self-agency, and (4) facilitating independent mobility. Thirteen principles were distilled to support decision making in enabling these outcomes in new-build and refurbishment projects. The results are of immediate use for decision makers who are responsible for HDMA-UGS planning, procurement, installation, and maintenance. The UGS role descriptions enable targeted design interventions for supporting children’s health and well-being, including during times of constrained outdoor time.