With the ongoing rise in renewable energy demand, offshore wind farms are rapidly expanding, increasing the need for advanced development and diagnostic techniques for submarine cables. These cables are essential for efficient and reliable power transmission. A critical issue with these submarine cables is the formation of internal hot spots, which can deteriorate the insulation’s performance and negatively impact the overall reliability of offshore wind energy infrastructure. This research focuses on developing an innovative real-time monitoring system to detect hot spots within submarine cable insulation under varying electrical loads. Experimental tests were conducted on a 66 kV-grade wet-type submarine cable specifically designed for offshore wind applications, applying incremental current loads ranging from 200 A to 500 A. Temperature changes within the insulation due to the generated heat were continuously monitored using Distributed Temperature Sensing (DTS). Additionally, to evaluate the DTS system’s precision, repeatability, and overall reliability, the measured temperatures were compared against values obtained from validated spot-type sensors. Experimental results showed a discrepancy of less than 1% between DTS and spot-type sensor measurements at a reference temperature of 60℃, demonstrating the high accuracy and reliability of the developed DTS-based monitoring system. The outcomes of this study suggest that the proposed monitoring system can significantly enhance the capability for early detection and continuous monitoring of hot spots, thereby improving the operational reliability of submarine cables employed in offshore wind energy installations.