Coffee is one of the most consumed beverages all over the world. Recently, it was reported that coffee contains several compounds, such as antioxidants, with positive effects to health. In order to evaluate the total antioxidant capacity (TAC) of beverages, analytical methods are needed. In this chapter, an electrochemical DNA-based biosensor was developed to assess the TAC of coffees. The construction of this biosensor consisted on the adenine-rich oligonucleotide immobilization on carbon paste electrodes. The application of this biosensor for the antioxidant evaluation is based on an in vivo assay by performing the exposition of DNA layers to: (1) an oxidant that induces oxidative damage on the DNA material, and (2) an antioxidant (in the presence of an oxidant) that promotes protective effect on the DNA immobilized onto the electrode. The developed DNA-based biosensor was suitable for rapid assessment of the TAC of coffee samples.