BACKGROUND/OBJECTIVES: A cross-sectional study was undertaken to evaluate fluid intake and hydration status in association with cognitive function among 230 adolescents (10–14 years of age) in Petaling Perdana, Selangor, Malaysia. SUBJECTS/METHODS: Urine color was used to measure hydration status, while fluid intake was assessed using the 15-item beverage intake questionnaire. Cognitive function was assessed using the Wechsler Intelligence Scale for Children, Fourth Edition. RESULTS: More than half of the adolescents were mildly or moderately dehydrated (59.6%) and only one-third (33.0%) were well hydrated. Among the daily fluid types, intakes of soft drinks (r = −0.180; P = 0.006), sweetened tea (r = −0.184; P= 0.005) and total sugarsweetened beverages (SSBs) (r = −0.199; P= 0.002) were negatively correlated with cognitive function. In terms of hydration status, cognitive function score was significantly higher (F-ratio = 4.102; P= 0.018) among hydrated adolescents (100.38 ± 12.01) than in dehydrated (92.00 ± 13.63) counterparts. Hierarchical multiple linear regression analysis, after adjusting for socio-demographic factors, showed that soft drinks (β = −0.009; P< 0.05) and sweetened tea (β = −0.019; P< 0.05) negatively predicted cognitive function (ΔR 2 = 0.044). When further control for sources of fluid, hydration status (β = −2.839; P< 0.05) was shown to negatively predict cognitive function (ΔR2 = 0.021). The above variables contributed 20.1% of the variance in cognitive function. CONCLUSIONS The results highlight the links between fluid intake (soft drinks, sweetened tea, total SSBs) and hydration status with cognitive function in adolescents. Interventions aimed at decreasing the consumption of SSBs and increasing hydration status through healthy fluid choices, such as water, could improve cognitive performance in adolescents.