Occupational heat stress is an escalating global health concern, particularly for outdoor workers exposed to rising temperatures due to climate change. This narrative review synthesizes evidence from 42 peer-reviewed articles and 13 policy documents published between 2014 and 2025, focusing on the health impacts, determinants, and adaptation strategies for outdoor workers. The review identifies a high prevalence of heat-related illnesses-including heat exhaustion, dehydration, kidney disorders, and productivity loss-across sectors such as agriculture, construction, and informal labour. Key vulnerability factors include individual health status, environmental conditions, and inadequate workplace policies. Adaptation strategies found to be most acceptable and effective include improved hydration, loose breathable clothing, scheduled rest breaks in shaded areas, and modification of work practices. Policy case studies from California, India, Qatar, and Europe highlight the importance of context-specific regulations, enforcement, and community outreach in reducing heat-related morbidity and mortality. However, significant gaps remain in the implementation of adaptive measures, especially for informal and vulnerable worker populations. The review underscores the urgent need for integrated, gender-sensitive, and enforceable adaptation strategies, alongside further research to strengthen resilience among outdoor workers facing increasing heat stress due to climate change.