Coronavirus disease-2019 (COVID-19) has infected millions of people with high lethality in the world, but little is known whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has impacts on triggering pediatric acute lymphoblastic leukemia (ALL). We present a case of a child with atypical clinical manifestation who developed B-cell acute lymphoblastic leukemia following a mild symptomatic COVID-19 infection. This case underlines the risks of potential oncogenic effects with the history of this viral infection and a state of immunosuppression.