Currently there is uncertainty concerning the prevalence of Hoarding Disorder (HD) due to methodological issues in the evidence base. Estimates have widely ranged from between 1.5% and 6% of the general population. This systematic review and meta-analysis therefore aimed to summarise and reliably estimate the prevalence of HD by employing strict inclusion criteria and using studies with sufficiently large samples. A systematic literature search was conducted to identify all relevant prevalence studies. Inclusion criteria were studies that reported working age adult HD prevalence rates and had sample sizes of at least 1009 participants. Eleven studies met criteria (n = 53,378), had low risk of bias and were originally based in developed countries. A random effects meta-analysis was then conducted, with subgroup moderator analysis and meta-regression. The pooled estimated prevalence for HD was 2.5% (CI 1.7-3.6%) and subgroup analyses revealed that prevalence rates were similar for both males and females. Guidance on the manner in which HD is assessed in future prevalence studies is provided and the clinical implications of the results discussed.