Background: The increasing COVID-19 cases and rising scientific interest on the role of ABO blood type in disease susceptibility and outcomes highlight the need to explore the associations among Filipinos, cognizant of racial and genetic predisposition. This study determined the relative risk of COVID-19 infection and disease outcomes with ABO blood type among Filipino patients. Methods: Employing an ambispective cohort, 550 consecutively-selected, hospitalized Filipino adult patients with SARS-CoV-2 RT-PCR result were included. Medical records of previously admitted patients were retrospectively reviewed and pertinent data were extracted. Prospectively, patients who were still admitted were recruited and followed-up. Risk ratio estimated the risk of primary (COVID-19 infection and severity) and secondary outcomes (ICU admission, intubation, and mortality). Findings: The risk of COVID-19 infection was 20% higher among type A (aRR=1·20, p=0·021) but was 19% lower among type O (aRR=0·84, p=0·023). Blood type A (aRR=1·25, p=0·041) was 25% at greater risk for severe-to-critical COVID-19 infection, while moderate COVID-19 was 62% higher among type AB (aRR=1·62, p=0.037) and was 54% lower among type O (aOR=0·65, p=0·010). ABO blood type did not predict any disease outcomes. Interpretation: ABO blood type was an independent predictor of COVID-19 infection and severity but not disease outcomes. Type A has higher risk for COVID-19 infection and severe-to-critical COVID-19, while type O had lower risk. This information can be utilized in identifying the population-at-risk, developing programs and interventions, increasing vigilance in medical management, and promoting adherence to precautionary and protective health-seeking behaviors. Funding: Philippine Council for Health Research and Development