Background: The 2022 multicountry mpox outbreaks predominantly affected gay, bisexual and other men who have sex with men (GBMSM) in non-endemic countries. Mpox vaccination is most effective if targeting GBMSM most at risk. It is unknown to what extent eligibility criteria for vaccination align with evidence on risk factors for mpox in GBMSM. Methods: We conducted an online self-report survey among GBMSM in the Netherlands between 29 July and 30 August 30, 2022, corresponding to the first month of the Dutch mpox vaccination campaign. GBMSM were recruited via advertisements on social media and gay dating apps. Participants reported on their sexual behaviour, mpox diagnosis, and/or vaccination since the start of the outbreak. Results: Of the 2,460 participants, 73 (3.0%) were diagnosed with mpox and 485 (19.7%) had been vaccinated. Using population sample weights, we estimated that, of the sexually active GBMSM population aged 18-80 years in the Netherlands, 1.1% had been diagnosed with mpox and 7.8% had been vaccinated. In multivariable logistic regression analyses, we found that current HIV-PrEP use, having 20 sex partners in the past 12 months and having sex in sex venues or at parties in the past two months were independent risk factors for mpox diagnosis. Conclusion: This study provides novel evidence on risk factors for mpox amongst GBMSM in the Netherlands that has guided a refinement of eligibility criteria for mpox vaccination. The dynamics of any future mpox outbreaks are unknown and continued adjustment of vaccination eligibility may be required to achieve sustained elimination.