Despite varying serum levels of 25(OH)D among schoolchildren in Ethiopia, data are lacking whether this affects their muscle function as measured by handgrip strength of these children. Handgrip strength may be used as a proxy indicator of muscle strength and function. This study evaluated the association between serum levels of 25(OH)D and handgrip strength among schoolchildren in Ethiopia. The study used a data set from a school-based cross-sectional study conducted on a total of 174 randomly selected schoolchildren from urban (N = 89) and rural (N = 85) settings of Adama Town and Adama Woreda, respectively. Handgrip strength, serum 25(OH)D levels, and anthropometry were measured for each child following standard procedures, while data on demographic characteristics of children and their parents were collected using a structured interviewer-administered questionnaire. A multivariable linear regression model was used to determine the association between serum vitamin D level and handgrip strength after adjusting for other predictors. The mean handgrip muscle strength of the students was 17.6 ± 6.9 kg. The average serum 25(OH)D for the group was 54.5 ± 15.8 nmol/L. On multivariable linear regression model, serum 25(OH)D level was significantly associated with handgrip strength (β = 0.06, P = .008) of the children after controlling for potential confounders. Other variables, female gender (β = -2.20, P = .004), age (β = 1.97, P < .001), height (β = .22, P < .001), weight (β = 0.33, P < .001), and triceps skinfold thickness (β = -0.19, P = .023), were identified to have significant association with handgrip strength of schoolchildren. Serum 25(OH)D levels had significant positive association with handgrip strength of Ethiopian schoolchildren. The results imply the need for incorporating school nutrition education on consumption of foods rich in important nutrients including vitamin D-rich foods in the school curricula and also enhancing behavioral change communication toward exposure to sunlight in the school to produce adequate vitamin D. Further longitudinal study involving a larger sample is recommended to confirm the findings.