The increasing adoption of EVs presents challenges in balancing energy supply and demand. Smart charging offers a potential solution. This study examined which factors support citizen engagement with smart charging, using the Capability-Opportunity-Motivation-Behavior model and related specific mechanisms of actions. Using an exploratory sequential mixed-methods design, Study 1 involved semi-structured interviews with 47 EV users in a major city in the Netherlands anticipating (increasing) grid congestion issues, applying a thematic abductive analysis. Findings informed a cross-sectional survey in Study 2 (N = 282), with hierarchical multiple regression analyses assessing the (relative) influence of key factors. Overall willingness for smart charging of EVs was high. Engagement with smart charging was influenced by opportunities (charging at home or using public charging stations, concerns regarding availability of a charging station, social norms about occupying charging stations), and motivational factors (preference for green energy, importance of grid stability, financial benefits, and trust in the charging system). Capabilities played a less prominent role. Using a mixed-methods approach, EV users’ willingness to engage with smart charging was shown to be shaped by individual as well as contextual factors. Findings offer valuable guidance for policymakers and stakeholders seeking to promote smart charging. These include, the importance of addressing charging infrastructure availability, social norms against prolonged use of public charging stations, and appealing to attitudinal drivers to promote smart charging behavior effectively. • The opportunity for home charging is a strong determinant for people's intention for smart charging. • Trust in the charging system's ability consistently predicts intention and acceptance of smart charging. • Environmental motives and decreasing grid congestion motives play a major role while financial incentives play no strong role.