Many women leaving jails are ill-prepared to follow recommended COVID-19 mitigation practices, including testing and vaccination. Low COVID-19-related health literacy, exposure to disinformation, and mistrust in authorities put women at increased risk. Research on this population has shown significant use of mobile devices for communication and web access and public Wi-fi for the internet. Using inductive (formative empirical research with the community) and deductive (theory-based) practices, we designed, developed, and pilot-tested a multimedia, culturally tailored web-based electronic health (eHealth) application to increase COVID-19-specific health literacy and promote testing and vaccination among women with criminal and legal system involvement (CLSI). The intervention included a serialized animated multimedia component and a telenovela-style series, complementing each other and addressing knowledge needs identified in the formative research phase of the project. The eHealth intervention was pilot-tested with 13 CLSI women by using online activity logs and semi-structured telephone interviews. Findings confirmed that eHealth interventions employing multimodal information delivery had increased chances of engaging audiences, especially when developed with input from the target population and are culturally tailored. In addition, using a web-based delivery optimized for mobile made the intervention accessible on various devices and decreased the risk of technical problems.