Ultra-thin, flexible, stretchable, and non-toxic sensors attract more and more attention as the need for more controlled non-invasive healthcare monitoring increases. Traditional conductive inks for electrode printing application require the use of metallic nanoparticles that can get very expensive to secure sensitivity, but the health aspect is often neglected. Graphene, a highly conductive, flexible, and high surface area material, has a much lower cost that makes it an ideal alternative. The rheological properties of the graphene ink developed allow it to be screen printed and inkjet printed, which allows it to be used in a wider range of applications. In this study, humidity sensors were printed with the as-prepared ink followed up with an annealing treatment. Annealing studies were performed to improve the conductivity by removing the polymer residues. The electronic properties and sensitivity of the as-fabricated electrode and sensor to a varied humidity range were measured using a four-point probe station in a closed chamber. The resulting electrochemical impedance spectra were further analyzed by fitting to an equivalent electrical circuit model to get the true resistance. The annealing study result can serve as a reference for conductive ink printing process optimization. It is anticipated that the screen-printed graphene electrodes hold great potential for developing flexible humidity sensors.