The near-surface mounted (NSM) fibre-reinforced polymer (FRP) technique has emerged as an effective method for strengthening concrete structures. While epoxy adhesives (EA) are widely used in NSM FRP systems due to their strong bonding properties, they have notable drawbacks, including reduced mechanical performance under high temperatures. Recently, the use of cement-based adhesives (CBA) as an alternative to epoxy adhesives has gained the attention of researchers due to their superior durability and resistance to elevated temperatures. However, further studies are needed to develop CBAs for NSM FRP systems that provide adequate mechanical bond performance. In addition, limited research has assessed the effectiveness of NSM FRP systems using CBA in strengthening concrete structures previously exposed to elevated temperatures, which is critical to avoiding the demolition and rebuilding of damaged concrete. Hence, this study aims to explore the potential of the NSM FRP technique using both EA and a newly developed CBA to strengthen concrete specimens either without prior thermal exposure or after being exposed to elevated temperatures (300 °C and 600 °C). The results reveal that the brittle behaviour and significant strength reduction in specimens strengthened with EA after thermal exposure highlight the limitations of EA. In contrast, specimens strengthened with CBA maintained ductile behaviour even when applied to concrete previously exposed to elevated temperatures. These findings suggest that CBA is a more reliable adhesive for NSM FRP systems in strengthening concrete exposed to high temperatures.