Stigma against people with hepatitis B virus (HBV) is a barrier to prevention, diagnosis and treatment of HBV in China. Our study examined an innovative intervention to reduce HBV stigma among men who have sex with men (MSM) in China. We extracted data from a randomized controlled trial conducted in May 2018, where the intervention consisted of crowdsourced images and videos to promote viral hepatitis testing and reduce HBV stigma. HBV stigma was assessed using a 20-item scale at baseline and four weeks post-enrolment. Participants were divided into three groups based on their exposure to intervention: full exposure, partial exposure and no exposure. Linear regression was used to determine associations between baseline stigma and participant characteristics. Data from 470 MSM were analysed. Mean participant age was 25 years old and 56% had less education than a college bachelor's degree. Full exposure to intervention was associated with significant stigma reduction (adjusted beta = -3.49; 95% CI = -6.11 to -0.87; P = .01), while partial exposure led to stigma reduction that was not statistically significant. The mean stigma score was 50.6 (SD ± 14.7) at baseline, and stigma was most prominent regarding physical contact with HBV carriers. Greater HBV stigma was associated with not having a recent doctor's visit (adjusted beta = 4.35, 95% CI = 0.19 to 8.52; P = .04). In conclusion, crowdsourcing can decrease HBV stigma among MSM in China and may be useful in anti-stigma campaigns for vulnerable populations in low- and middle-income countries. © 2019 John Wiley & Sons Ltd.