This study focuses on the factors influencing the intention of citizens to be involved in participatory budgeting (PB) on the municipal level via different electronic communication channels. Having classified such factors based on a literature review, we construct a comprehensive model of citizens’ participation in electronic PB (e-PB) which comprises the following three blocks of factors: (1) citizens’ attitude towards electronic communication with public authorities; (2) citizens’ social capital (as related to their municipality); (3) citizens’ motivation to participate in e-PB. To empirically verify interconnections and influence of different factors on citizens’ involvement in e-PB, we conducted a survey. To this end, we developed a questionnaire to poll the inhabitants of the Yuzhno-Primorskiy municipality of St. Petersburg. Using the collected information on 259 respondents, the developed model was estimated using the partial least squares structural equation modeling approach (PLS-SEM). We demonstrate that citizens’ motivation has the highest, statistically significant influence on the intention of people to be involved in PB. The found mediation effects allowed to confirm the influence of social capital and attitude towards electronic communication on citizens’ motivation to participate in e-PB. Based on the obtained results, we provide relevant recommendations for the administration of the Yuzhno-Primorskiy municipality, which are expected to help the authorities more actively involve the citizens of the municipality in participatory budgeting.