Abstract: Conducting polymers (CPs), including poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), are promising coating materials for neural electrodes. However, the weak adhesion of CP coatings to substrates such as platinum–iridium is a significant challenge that limits their practical application. To address this issue, we used femtosecond laser-prepared hierarchical structures on platinum–iridium (Pt–Ir) substrates to enhance the adhesion of PEDOT:PSS coatings. Next, we used cyclic voltammetry (CV) stress and accelerated aging tests to evaluate the stability of both drop cast and electrodeposited PEDOT:PSS coatings on Pt–Ir substrates, both with and without hierarchical structures. Our results showed that after 2000 CV cycles or five weeks of aging at 60 °C, the morphology and electrochemical properties of the coatings on the Pt–Ir substrates with hierarchical structures remained relatively stable. In contrast, we found that smooth Pt–Ir substrate surfaces caused delamination of the PEDOT:PSS coating and exhibited both decreased charge storage capacity and increased impedance. Overall, enhancing the stability of PEDOT:PSS coatings used on common platinum–iridium neural electrodes offers great potential for improving their electrochemical performance and developing new functionalities.