Health information literacy (HIL), as an essential part of the wellbeing of citizens, is a crucial indicator used to measure a country's primary public health level. The present study collected 1051 samples in southern China to examine the factors predicting HIL. The results showed that males, those less educated, and older adults had lower HIL. Television exposure, unofficial Internet exposure, trust in government and trust in doctors and medical institutions were positively associated with HIL. In contrast, newspapers, radio exposure and trust in web celebrities were negatively associated with HIL. Official Internet media exposure helps to bridge the HIL knowledge gap generated by differences in education level, while trust in celebrities-especially web celebrities-could widen the HIL knowledge gap. This study extends the knowledge gap theory in health communication in the Chinese context and provides pathways for future health interventions.