E-government, social media, and dialogic communication share the same common goals, that is to increase transparency and civic engagement. Hence, the present study sheds light on the understudied interrelationships between e-government development, social media dialogic principles, and online citizens’ engagement in the context of Greek smart cities. To this end, the Facebook pages of 64 Greek smart cities with varying degrees of e-government development were analyzed to determine the implementation of dialogic principles, and the level of citizens’ engagement with social media content. Results suggest that social media communication of smart cities in Greece is based on the principles of information of interest to stakeholders and generation of new visits. E-government development was an important positive predictor for information of interests to stakeholders. Dialogic principles influenced in varying ways citizens’ social media engagement. Important implications regarding smart city managers are discussed.