The study was to develop the e-healthy diet literacy (e-HDL) questionnaire based on the comprehensive health literacy (HL) conceptual framework, to examine the association among HL, e-HDL, health behaviors and outcomes. A nationwide study was conducted on 1342 adults aged 18 years and above, between April and September 2017. Multi-stage random sampling was used to recruit the participants from four regions and 19 cities and counties in Taiwan. HL and e-HDL were measured by HLS-SF12 and the e-healthy diet literacy questionnaire (e-HDLQ), respectively. Socio-demographics, behaviors (e.g. smoking, drinking and exercising) and health outcomes were also measured. Principal component analysis (PCA), linear regression models and logistic regression models were used. The mean age was 33.9 ± 11.4 years. The e-HDLQ was constructed with 11 items. A positive association between HL and e-HDL was found. In the multivariate analysis, HL and e-HDL were significantly lower in men and higher in those who used Facebook for searching information. HL was positively associated with the ability to pay for medication, and social status. The e-HDL was lower in older participants, and people who searched for healthy cooking, healthy food places or weight control, as compared with ones searched for nutritional therapies, while positively associated with education. Both HL and e-HDL were positively associated with health status and physical activities. In conclusion, the valid e-HDL survey tool was developed for general public use. The e-HDL strongly associated with HL, while both were determined by gender, online searching means and linked to health behaviors and outcomes.