Around 45% of patients with melanoma are older than 65 years. In recent years, immunotherapy has proven very effective for metastasised melanoma. The aim of this study was to investigate the time trends in treatment strategies and survival in older versus younger patients with synchronous metastasised melanoma. We included all patients diagnosed between 2000 and 2019 from the Netherlands cancer registry. We analysed changes in first-line systemic treatment using multivariable logistic regression models, stratified by age (<65, 65–75, and ≥75). Changes in overall survival were studied using multivariable Cox regression analysis. A total of 2967 patients were included. Immunotherapy prescription increased significantly over time for all age groups (<65 years: 11.8% to 64.9%, p < 0.001; 65–75 years: 0% to 68.6%, p < 0.001; >75 years: 0% to 39.5%, p < 0.001). In multivariable analyses, overall survival improved for patients aged <65 and 65–75 (HR 0.96, 95% CI 0.92–1.00 and HR 0.95, 95% CI 0.89–1.00, respectively), but not in patients over 75 (HR 0.98, 95% CI 0.91–1.05). In conclusion, overall survival has improved in patients with synchronous metastasised melanoma aged <75 years, but not in patients aged 75 years or older. This might be explained by lower prescription rates of immunotherapy in this age group.