In this work we present a very simple preparation procedure of a poly(ethylene oxide) (PEO)-based crosslinked polymer electrolyte (XPE) for application in sodium-ion batteries (NIBs). The polymer electrolyte, containing NaClO4 as Na+ source, is prepared by rapid, energy saving, solvent-free photopolymerization technique, in a single step. Thermal, mechanical, morphological and electrochemical properties of the resulting XPE are thoroughly investigated. The highly ionic conducting (>1 mS cm−1 at 25 °C) polymer electrolyte is used in a lab-scale sodium cell with nanostructured TiO2 working electrode. The obtained results in terms of ambient temperature cycling behaviour (stable specific capacity of about 250 mAh g−1 at 0.1 mA cm−2 and overall remarkable stability, for a quasi-solid state Na polymer cell, upon very long term cycling exceeding 1000 reversible cycles at 0.5 mA cm−2 corresponding to > 5000 h of continuous operation) demonstrate the promising prospects of this novel XPE to be implemented in the next-generation NIBs conceived for large-scale energy storage systems, such as those connected to photovoltaic and wind factories.