This study investigates projected changes in heat stress in a changing climate and their impacts on population exposure, work performance, and mortality in the Arabian Peninsula (AP). The findings demonstrate an intensification in future heat stress across the AP, with a projected increase in extreme caution and danger days under SSP5-8.5, compared to SSP2-4.5 and SSP1-2.6 scenarios. The coastal cities are projected to experience higher heat stress intensity and more heat stress days than inland cities, making them more vulnerable to the impacts of climate change. By 2100, the average population exposure to extreme caution days will increase by 1.38–2.5 and danger days by 0.13–1.0 million people-days under the selected SSPs, relative to the baseline period. Coastal regions are particularly vulnerable, with work performance potentially declining by 6%–21%. The heat-related mortality risk ratio will increase by 2.3–35.4 times under the selected SSPs across the entire AP. The implications of these findings might influence the response and mitigation strategies, highlighting the critical necessity for focused policy initiatives aimed at reducing emissions and improving adaptive capacity in the region to address climate change.