The metabolic and protein biomarkers are the most significant detection targets for the point-of-care disease diagnosis and healthcare. The chronic diseases are among the world’s leading causes of mortality, and the COVID-19 pandemic is continuously burdening the global health, especially impacting the low-income, resource-limited regions. Accurate point-of-care detection of biomarkers is an important monitoring strategy for chronic disease development. Early detection of infectious disease outbreaks can reduce the ultimate size of the outbreak and the overall morbidity and mortality due to the disease, in which diagnosis plays an important role. As available diagnostic technologies require well-trained personnel, expensive equipment and complex assay procedure and consume a large amount of time in medical laboratories, there is an urgent need for low-cost portable platforms that can provide fast, accurate, and ideally multiplexed diagnosis of infectious diseases at the point of care. This thesis reports on the design, fabrication, and demonstration of electrochemical point-of-care detection systems for metabolic and protein biomarkers. Rapid results have been achieved by employing electrochemical enzymatic reactions on devices with simple fabrication and preparation. The systems have demonstrated high sensitivity and specificity comparable to state-of-the-art laboratory tests. The works reported in this thesis show strong potential to lead to portable systems for point-of-care diagnosis.