Exposure to indoor radon, a naturally occurring radioactive gas, is one of the main causes of lung cancer worldwide. Although radon tests are easily accessible in most countries, and protective actions are effective and relatively easy to apply, the levels of radon testing and subsequent home remediation remain lower than aimed for. Public engagement, particularly through internet, may contribute to addressing this value-action gap. Given their role as common interaction points between citizens and public services, this research analyzed radon websites from a stakeholder engagement perspective. The rich database assembled, of websites in eight European countries with highly radon prone areas, provides for the empirical novelty of the study. The website evaluation relied on internet communication metrics adapted for radon risk mitigation. This included availability of radon information, accessibility, stakeholder interaction, dialogue, responsiveness, content and design, and transparency and openness. Unexpectedly, results show that availability of radon information on the internet in radon prone areas is often limited and poor, as for instance only three internet pages dedicated to radon have been found. Radon websites should be improved with consistent information supported by engaging stories, provide for personalized features, support stakeholder feedback and dialogue, and include the use of social media. We conclude by consolidating the analysis into a list of recommendations for health communication practitioners, which should support radon risk mitigation, and contribute to improving public health, particularly decreasing the numbers of lung cancers. The effect of radon information available on internet pages on changing protective behaviors is suggested for future research.