Electrochemiluminescence devices (ECLDs) have several advantages over organic light-emitting diodes (OLEDs), such as simple structure, low fabrication cost, and manufacturability under air ambience. However, the low light-emission efficiency of ECLDs limits their commercial applications. In this study, a Pd nanoparticle (NP)-anchored TiO₂ nanorod (NR) electrode (PTNE) is used to enhance the light-emission properties of ECLDs. The electrochemical catalytic properties of the Pd NPs are analyzed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) as a function of the Pd NP size. The PTNE-based ECLDs with the optimal size of Pd NPs exhibit significant reduction in the minimum driving voltage for multi-color ECLDs than that for the ECLDs with FTO and bare TiO₂-NR electrodes. This improvement is achieved by maximizing the surface-to-volume ratio of the electrodes and enhancing the electron transfer rate between the Pd NP catalysts and luminophores of the ECL composite solution.