It was found that N,N’-bis(naphthalidene)-2-aminobenzylamine (BNA) containing PVC membranes display a good Dy(III) selectivity in comparison to most common first and second main group elements (representative), transition, and lanthanide ions. Therefore, we investigated its use as an neutral ion carrier, for preparing a Dy(III) PVC-membrane electrode. The primarily studied PVC-based membranes contained sodium tetraphenyl borate (NaTPB) as an anionic additive, and were tested by using different solvent mediators such as benzyl acetate (BA), nitrobenzene (NB), and dibutyl phthalate (DBP). The effects of the membrane composition, pH, and additive anionic influence on the response properties were investigated. The best performance was obtained with a membrane containing 30% PVC, 66% NB, 2% BNA, and 2% NaTPB. The electrode shows a Nernstian behavior (slope of 20.7 ± 0.4 mV per decade) over a very wide iron ion concentration range (1.0 × 10-6-1.0 × 10-2 M) and has a low detection limit (5.2 × 10-7 M). The potentiometric response of the sensor is independent of pH of the solution in the pH range 2.5–8.6. The proposed sensor has a very low response time (~7 s).