OBJECTIVE: Occupational heat stress, driven by high ambient temperatures, humidity, and radiant heat impairs health, safety, and productivity. Among the interventions for mitigating heat strain, wearable cooling technologies [eg, water/ice, phase-change materials (PCM), ventilated/evaporative garments] is increasingly used, but their comparative effectiveness remains unclear. This systematic review aimed to evaluate the effectiveness of wearable cooling intervention on physiological and perceptual outcomes during heat exposure. METHODS: Adhering to PRISMA guidelines (PROSPERO: CRD42025631559), we searched PubMed, Embase, and Scopus (February 2026) for randomized or non-randomized intervention trials among workers or acclimatized adults. Data were extracted as mean/standard deviation (or transformed equivalents) and pooled using random-effects meta-analysis. Heterogeneity (I2), small-study effects (Egger’s test) and sensitivity/subgroup analyses of cooling modalities were performed. Risk of bias (RoB 2, ROBINS-I) and certainty (GRADE) were assessed. RESULTS: Sixty-nine studies were included in our review. Post-exposure, wearable cooling significantly reduced rectal temperature [mean difference (MD) -0.24°C; 95% confidence interval (CI) -0.37– -0.1; I=43.91%], gastrointestinal temperature (MD -0.26°C; -0.52– -0.001; I=98.13%), skin temperature (MD -1.14°C; -1.85– -0.42; I=96.56%), and heart rate (MD -7.69 bpm; -11.22– -4.15; I=73.19%). Egger’s tests suggested possible small-study effects for skin temperature and heart rate but not for core temperatures. Subgroup analyses indicated more consistent benefits with water/ice and PCM garments. Overall certainty ranged from low to very low due to risk of bias, inconsistency, and imprecision. CONCLUSIONS: Wearable cooling attenuates physiological heat strain and improves thermal comfort, particularly via water/ice and PCM systems. Given high heterogeneity and low certainty, adequately powered, standardized, head-to-head trials are needed.