Background: The aim of this study was to evaluate hematological parameters in children with COVID-19 and determine the effects of inflammatory biomarkers on the assessment of hospitalization. Methods: This retrospective single-center study was performed on 633 children with COVID-19 between March 2020 and January 2021. The study population was separated into two groups: inpatients (n = 83) and outpatients (n = 550). Univariate and multivariate logistic regression was applied to identify risk factors for hospitalization. Results: Lymphopenia (n = 228, 36%) was found mainly to be a hematological abnormality in all cases. Compared with outpatients, inpatients had significantly higher white blood cell (WBC) (p = 0.005), lymphocyte (p < 0.001), and platelet counts (p = 0.036), and significantly higher red cell distribution width (p = 0.001), C-reactive protein (CRP) (p = 0.003), procalcitonin (p = 0.001), d-dimer (p < 0.001), and lymphocyte to monocyte ratio values (p = 0.004). On the other hand, they had significantly lower values of hemoglobin (p < 0.001), neutrophil to lymphocyte ratio (p = 0.024), platelet lymphocyte ratio (p = 0.001), derivated neutrophil to lymphocyte ratio (p = 0.037), and mean platelet volume to lymphocyte ratio (p < 0.001). ROC analysis showed that WBC, CRP, and procalcitonin cutoff values were the best discriminated between inpatients and outpatients. The results for the areas under the curve of WBC, CRP, and procalcitonin used to assess patients’ hospitalization were 0.595 (95% CI 0.519–0.670, p = 0.005), 0.599 (95% CI 0.527–0.672, p = 0.003), and 0.599 (95% CI 0.525–0.673, p = 0.004), respectively. Conclusion: We suggest that high WBC and procalcitonin levels can be used as independent predictors of hospitalization in children with COVID-19.