The interaction of macrocyclic compounds like crown ethers and UO₂²⁺ has been studied by electrochemical methods. A modified carbon paste electrode incorporating benzo-15-crown-5 (B15C5) was used to evaluate the electron transfer reaction of UO₂²⁺ by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Electrochemical impedance studies showed that charge transfer resistance was less for the B15C5-modified electrode than for the plain carbon paste electrode (PCPE). On the basis of these observations, a UO₂²⁺-sensitive crown ether chemically modified electrode (CME) for trace analysis was fabricated and investigated in aqueous solutions. It was found that a 5% B15C5–CME for UO₂²⁺ showed a better voltammetric response than did the PCPE. UO₂²⁺ could be quantified at sub-µg/mL levels by differential pulse voltammetry with a detection limit of 0.03 µg/mL. By differential pulse adsorptive stripping voltammetry, UO₂²⁺ could be quantified in the working range of 0.002–0.2 µg/mL, with a detection limit of 1.1 µg/L. Simultaneous determination of UO₂²⁺, Pb²⁺, and Cd²⁺ was possible. The method was successfully applied to the determination of UO2²⁺ in synthetic, as well as real, samples; the results were found to be comparable to those obtained by inductively coupled plasma-atomic emission spectroscopy.