Sitagliptin, an oral antidiabetic drug, is an effective medication for lowering blood glucose level either as monotherapy or in combination with other antidiabetic drugs. This work aims for the fabrication of a potentiometric sensor for sitagliptin detection. The sensor was designed by doping the polyvinyl chloride polymeric ion-selective membrane with calix[4]arene as an ionophore which highly improved the linearity range (1 × 10−6—1 × 10−2 M), sensitivity, selectivity and limit of detection (6.3 × 10−7 M) compared to ionophore-free membrane. The method was then validated according to the International Council for Harmonization (ICH) guidelines. The sensor was successfully employed to determine sitagliptin in bulk and pharmaceutical dosage form without any pre-treatment steps. Moreover, to demonstrate the deployability of the proposed sensor; it has been applied for the dissolution testing of sitagliptin by in-line continuous monitoring of sitagliptin release as a function of time from the pharmaceutical dosage form into the dissolution medium. This in-line dissolution monitoring has many advantages such as there is no need for the frequent sampling followed by the complicated procedures of samples treatment. Finally, the proposed potentiometric method was evaluated using the analytical eco-scale and has proved to be excellent green analysis in which solvent consumption and pre-treatment of samples were not necessary for its application.