This study evaluates the impact of urban material property modifications on thermal comfort using computational fluid dynamics(CFD) simulations, focusing on how changes in surface material thermal characteristics influence the urban thermal environment. The intensification of urban heat island (UHI) effects due to climate change has increased heat stress and health risks. While localized adaptation measures have been examined, comprehensive city-wide approaches remain insufficiently explored. This research addresses that gap by analyzing material modifications to improve urban thermal comfort and mitigate UHI. CFD simulations were performed for Jeonju New Town, South Korea, under various scenarios altering the thermal properties of surface materials such as asphalt, concrete, and green spaces. The Universal Thermal Climate Index (UTCI) assessed thermal comfort, while surface temperature measurements evaluated heat stress mitigation. The results indicated that reflective and adaptive materials significantly reduced surface temperatures and thermal stress. For instance, the peak surface temperature declined from 46.94 °C to 41.16 °C, while UTCI values decreased from 32.49 °C to 30.03 °C. These findings underscore the importance of material selection in mitigating UHI effects. Additionally, this study highlights the utility of UTCI as a comprehensive thermal comfort indicator, with future research suggesting that AI and digital twin technologies could further enhance urban climate adaptation strategies.