Background Public safety personnel (PSP) experience high rates of mental health disorders but have limited access to treatment. To improve treatment access, there is a growing interest in offering internet-delivered cognitive behaviour therapy (ICBT) to PSP. As attitudes towards ICBT can both impact and inform ICBT implementation efforts, this study examines perceptions of ICBT among PSP who viewed a poster (a commonly used method of advertising ICBT) or a poster supplemented with a story of a PSP who benefitted from ICBT. Methods Participants (N = 132) from various PSP sectors were randomly assigned to view a poster or a poster and a story. Participants then completed an online survey assessing their perceptions of ICBT using both qualitative and quantitative questions. We used a mixed-methods approach to analyze the data. Results No differences in perceptions of ICBT were identified between the conditions. Ratings of credibility, treatment expectancy, anticipated treatment adherence, and acceptability suggested that PSP had positive perceptions of ICBT. Most participants (93%) reported that they would access ICBT if they needed help with mental health concerns. Participants ranked therapist-guided ICBT as their second most preferred treatment, with psychologists ranked first. Female participants found ICBT more credible than male participants. More experienced PSP reported lower acceptability and anticipated adherence to ICBT. Conclusions The findings suggest that many PSP are likely to be receptive to ICBT even when a simple poster is used as a method of informing PSP of this treatment option. Further attention to improving the perceptions of ICBT among certain groups may be warranted.