In our study, a selective and sensitive determination method was developed for Cu(II) ions by spectrofluorimetry. For this purpose, a polymeric membrane was prepared to determine Cu(II) ions by curing crosslinkers, functional monomers, and photoinitiators under UV light. The membrane was characterized, and the optimum conditions for determining Cu(II) ions were systematically investigated. The detection was performed at pH 5.0 in as little as 20 seconds at excitation and emission wavelengths of 376 nm and 455 nm, respectively. The linear range was 7.86.10-9-1.57.10-7 mol/L, and the method's detection limit was 2.24.10-9 mol/L. In addition, the sensor's repeatability, stability, and life were examined, and recovery studies were conducted. As a result, the developed method has been successfully applied to wastewater samples as a real sample. In addition, determining Cu(II) ions at low concentrations can be done quickly, reliably, and with high selectivity and sensitivity.