To estimate the seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection among hospitalized children aged between 1 and 12 years. A cross-sectional study was conducted to determine the seroprevalence of SARS-CoV-2 antibodies among hospitalized children at a tertiary care hospital in the North-East region of India for a period of 13 months (October 2022-November 2023). The presence of SARS-CoV-2 antibodies was estimated using enzyme-linked immunosorbent assay method. Sociodemographic characteristics and clinical profile of the participants were analyzed. The seroprevalence of SARS-CoV-2 infection among hospitalized children aged between 1 and 12 years was estimated to be 98.4%. This was comparable for children between the age groups 1-5 years (97.9%) and 6-12 years (99.1%) (P-value = .478). The most commonly reported symptoms among the seropositive children were fever (76.8%), nasal stuffiness (69.5%), cough (67.8%), diarrhea (23.6%), and nausea/vomiting (23.2%). None of the study participants had a prior history of laboratory confirmed coronavirus disease (COVID-19) infection in the past and none were vaccinated against COVID-19. Results of the univariate analysis showed that there was no significant difference between the seropositive and seronegative children in the distribution of sociodemographic characteristics, clinical profile, and laboratory findings. Our study observed a remarkably high anti-SARS-CoV-2 seropositivity rate of 98.4%, suggesting a significant under-recognized burden of COVID-19 in the pediatric population. The findings highlight the need for continued preventive measures and the development of age-appropriate vaccination strategies, particularly in tropical settings.