Introduction: Exercise is essential for maintaining physical fitness, and weight training is a popular form that can cause delayed onset muscle soreness (DOMS). Although cold and warm water immersion are known to reduce DOMS, direct comparative studies are limited. This study compares their effectiveness in reducing calf muscle DOMS after weight training. Aims: This study aims to determine the comparative effectiveness of cold water immersion and warm water immersion on the intensity of delayed onset muscle soreness in the calf muscles following weight training. Method: This study employed a quantitative quasi-experimental design with a posttest-only three-group approach. A total of 36 participants were selected using total sampling. DOMS intensity was measured using the Visual Analogue Scale (VAS) on the left calf at 24, 48, and 72 hours after weight training. Results: This study showed that warm water immersion significantly reduced VAS scores compared to cold water immersion (p = 0.006) and the control group (p = 0.032), while no significant difference was observed between cold water immersion and the control group (p = 0.605), indicating the superior effectiveness of warm water immersion. Conclusion: Warm water immersion is significantly more effective than cold water immersion and the control group in reducing calf muscle DOMS after weight training.