An instantaneously usable fully printed paper-based three-electrode system was developed for use as cost-effective and disposable biosensors and ion sensors. The three-electrode system was composed of a carbon working electrode, counter electrode, and an integrated Ag/AgCl reference electrode with an inner saturated KCl layer and a liquid junction. The potential stability of the reference electrode was approximately 99 h. The setup time was less than 1 min.