Background: eHealth literacy is gaining importance for maintaining and promoting health. Studies have found that individuals with high eHealth literacy are more likely to adopt healthy eating, exercise, and sleep behaviors. In addition, previous studies have shown that various individual factors (eg, frequency of seeking information on health issues, degree of health concern, frequency of eating organic food, and students' college major) are associated with eHealth literacy and health-promoting lifestyles. Nevertheless, few studies have explored the associations among individual factors, eHealth literacy, and health-promoting lifestyles among college students. Moreover, there is a lack of studies that focus on eHealth literacy as a predictor of psychological health behaviors. Objective: To examine the associations among various individual factors, eHealth literacy, and health-promoting lifestyles. Methods: The eHealth Literacy Scale is a 12-item instrument designed to measure college students' functional, interactive, and critical eHealth literacy. The Health-promoting Lifestyle Scale is a 23-item instrument developed to measure college students' self-actualization, health responsibility, interpersonal support, exercise, nutrition, and stress management. A nationally representative sample of 556 valid college students in Taiwan was surveyed. A questionnaire was administered to gather the respondents' background information, including the frequency of seeking information on health issues, the frequency of eating organic food, the degree of health concern, and the students' major. We then conducted a multiple regression analysis to examine the associations among individual factors, eHealth literacy, and health-promoting lifestyles. Results: The study found that factors such as medical majors (t(550=)2.47-7.55, P<.05) and greater concern with health (t(550)=2.15-9.01, P<.05) predicted college students' 4-6 health-promoting lifestyle dimensions and the 3 dimensions of eHealth literacy. Moreover, critical eHealth literacy positively predicted all 6 health-promoting lifestyle dimensions (t(547)=2.66-7.28, P<.01), functional literacy positively predicted 2 dimensions (t(547)= 2.32-2.98, P<.05), and interactive literacy predicted only the self-actualization dimension (t(547)= 2.81, P<.01). Conclusions: This study found that participants who majored in medical fields had greater concern with their health and frequently sought health information, exhibited better eHealth literacy, and had a positive health-promoting lifestyle. Moreover, this study showed that college students with a higher critical eHealth literacy engaged better in health-promoting activities than those with functional and interactive literacy.