There has been growing recognition of the interconnections between human health, environmental sustainability, and ecosystem resilience. Positioning active outdoor play as a potential catalyst and ally in advancing human, animal, and environmental health, this study developed and validated a framework linking active outdoor play and One Health. The framework development followed a structured, multi-step process incorporating a scoping review, conceptual mapping, and expert consultations. Based on the results of the scoping review, a conceptual mapping exercise was undertaken to visually represent the interconnections between active outdoor play and One Health, which was then validated by key informants (n = 16) selected based on their expertise and leadership in the relevant topic areas. A total of 23 scholarly articles addressed the potential interconnectedness of active outdoor play, human-animal relationships, and environmental responsibility. Three themes emerged: 1) outdoor play environments and climate resilience (n = 6), 2) human-animal interactions and public health (n = 10), and 3) environmental stewardship and responsibility toward planetary health (n = 7). Nine policy documents were identified, of which eight did not make direct references to active outdoor play. Informed by the evidence, the PLAY+ (Play, Land, Animals, You and +) framework was created. Insights from an expert survey further refined the framework. While the framework highlights the interconnected benefits of active outdoor play across human, animal and environmental health domains, it is equally important to recognize associated risks and unintended consequences. As such, the framework should be views as conceptual, heuristic tool that encourages precautionary approaches, continued empricial evaluation, and context-sensitive implementation.