This study aimed to assess cognitive function and associated factors among school age children in Goba Town, South-Eastern Ethiopia. School based cross-sectional study was employed on 131 school children age 8–11 years. Cognitive function was assessed by Kaufman Assessment Battery for Children (KABC-II) and Ravens colored progressive matrices (Raven’s CPM) test. Descriptive statistics, independent t test, one way ANOVA and logistic regression were used in statistical analysis. The mean (±SD) score of Raven’s CPM test and triangles test was 22.02(±4.79) and 15.17 (±3.24) respectively. The mean (±SD) for short term memory measures such as word order, hand movement number recall was 15.66 (±3.03), 9.09 (±2.88) and 8.91 (±2.19) respectively. The mean score (±SD) of pattern score was 9.63 (±4.43). There was a statistically significant mean difference in hand movements and pattern score between those children who currently used iodized salt and non iodized salt(p<0.05). Wealth index was associated with rovers score (P=0.044). Breakfast consumption was statistically associated with triangles (P<0.001). Those children who had eaten breakfast less than seven days in last week had above 3 times higher odd to score RPM below average(AOR=3.05; 95% CI: 1.07–8.68). This might implicates that promotion of iodized salt intake, improving dietary diversity, improving breakfast eating habit, and improving wealth index are important modifiable factors of cognitive function.