Purpose The purpose of this paper is to investigate the direct effects of eHealth literacy, perceived competence, perceived electronic word-of-mouth (eWOM) credibility and price perception on consumers' willingness to purchase online mental health services. This study also examines the mediating role of perceived information quality on the eHealth literacy-consumers' willingness to purchase online mental health services relationship and the moderating roles of perceived eWOM credibility and price perception on the perceived competence-consumers' willingness to purchase online mental health services relationship. Design/methodology/approach Based on an extensive literature review, a conceptual model was developed. The research design was cross-sectional. A total of 400 respondents participated in the self-administered survey. After discarding some questionnaires due to incompleteness and lack of variance, a total of 367 responses was used in final data analysis. Partial least square structural equation modeling (PLS-SEM) was used to test the proposed model. Findings eHealth literacy, perceived competence, perceived eWOM credibility and price perception were found to have significant positive direct effects on consumers' willingness to purchase online mental health services. Perceived information quality was found to have a significant partial mediating effect on the eHealth literacy-consumers' willingness to purchase online mental health services relationship. Both perceived eWOM credibility and price perception were found to have significant positive moderating effects on the perceived competence-consumers' willingness to purchase online mental health services relationship. Originality/value Studies concerning online mental health services from a marketing or business perspective is almost non-existent. Therefore, this study contributes to the scarce literature in that context. This is the first study that has investigated how eHealth literacy, perceived information quality, perceived competence, perceived eWOM credibility and price perception influence consumers' willingness to purchase online mental health services.