Civic online participation platforms offer valuable opportunities to involve citizens in local governance and benefit from collective intelligence. Yet, vulnerable groups, such as older adults, people with disabilities, and the less educated, are often underrepresented in online political engagement. Aiming to empower these citizens to raise their voice online, we conducted two studies using an inclusive-by-design approach for developing an online civic engagement platform. In the first study, 39 individuals from two digitally low-performing European countries were surveyed about functions and features that would motivate and support their online participation. In the second study, focus groups with 13 digital and AI experts identified technical and informational requirements for effective use of the features desired by citizens. Our findings show the wishes for accessible, unbiased and secure AI-driven civic engagement platforms with transparency and user education about AI tools. In particular, chatbots require clear disclaimers and user guidance. Once citizens have been involved in the technical design process, both technical and informational feature preferences must be taken into account to avoid access and usability barriers or misunderstandings during the platform’s use. This is important to facilitate participation, especially for citizens from vulnerable groups.