Objective Assessing the level of eHealth literacy in a population is essential to designing appropriate public health interventions. This study aimed to assess eHealth literacy among adult internet users in Lebanon, recruited through social media and printed materials. The study examined the relationship between internet use, perceived eHealth literacy, and sociodemographic characteristics. Methods A cross-sectional study based on a web-based questionnaire was conducted between January and May 2020. The survey assessed internet use and eHealth literacy using the homonymous scale (eHEALS) in English and Arabic. Cronbach's alpha and factor analyses were used to evaluate eHEALS’ psychometric properties. A generalized linear model was used to identify factors predicting the eHEALS. Results A total of 2715 respondents were recruited mostly through Facebook (78%) and printed materials (17%). Most respondents completed the survey in English (82%), were aged 30 ± 11 years, female (60%), Lebanese (84%), unmarried (62%), employed (54%), and with a graduate-level education (53%). Those who completed the eHEALS questionnaire ( n = 2336) had a moderate eHealth literacy ( M = 28.7, SD = 5.5). eHEALS was significantly higher among older females with a high education level, recruited from Facebook, Instagram, or ResearchGate, and perceived the Internet as a useful and important source of information. Conclusions Future internet-delivered public health campaigns in Lebanon should account for moderate-to-low levels of eHealth literacy and find ways to engage older males with low education levels representing neglected segments (e.g. Syrians). To be more inclusive, campaigns should reach neglected population segments through non-digital, community-based outreach activities.