Objective Little is known about the age-specific prevalence of hoarding and obsessive compulsive symptoms (OCS), particularly in older age groups. The objectives of this study were to estimate the age-specific prevalence, severity, and relationships between hoarding and OCS in males and females using a large population-based sample. Methods We assessed the age-specific prevalence rates of hoarding disorder (HD) and OC disorder (OCD) in males and females (at various age ranges between 15 and 97 years) from the Netherlands Twins Register (N = 15,194). Provisional HD and OCD diagnoses were made according to Diagnostic and Statistical Manual of Mental Health Disorders, 5th Edition, criteria using self-report measures. We also assessed hoarding and OCS severity in the various age groups and explored specific hoarding and OCS patterns (e.g., difficulty discarding, excessive acquisition, clutter, checking, washing, perfectionism, and obsessions) with age. Results Prevalence of provisional HD diagnoses (2.12%) increased linearly by 20% with every 5 years of age (z = 13.8, p < 0.0001) and did not differ between males and females. Provisional OCD diagnoses were most common in younger individuals and in individuals over age 65. Co-occurring OCD increased hoarding symptom severity (coefficient: 4.5; SE: 0.2; 95% CI: 4.1–4.9; t = 22.0, p < 0.0001). Difficulty discarding for HD and checking behaviors for OCD appeared to drive most increases in these diagnoses in older ages. Conclusion Increased prevalence and severity of HD with age appears to be primarily driven by difficulties with discarding. Increases in OCD prevalence with older age were unexpected and of potential clinical relevance.