It is unclear whether moderate-to-vigorous physical activity (MVPA) is associated with a lower mortality risk, over and above its contribution to total physical activity volume.46,682 adults (mean age: 64 years) were included in a meta-analysis of nine prospective cohort studies. Each cohort generated tertiles of accelerometry-measured physical activity volume and volume-adjusted MVPA. Hazard ratios (HR, with 95% confidence intervals) for mortality were estimated separately and in joint models combining volume and MVPA. Data was collected between 2001 and 2019 and analyzed in 2023.During a mean follow-up of 9 years, 4,666 deaths were recorded. Higher physical activity volume, and a greater contribution from volume-adjusted MVPA, were each associated with lower mortality hazard in multivariable-adjusted models. Compared to the least active tertile, higher physical activity volume was associated with a lower mortality (HRs: 0.62; 0.58, 0.67 and 0.50; 0.42, 0.60 for ascending tertiles). Similarly, a greater contribution from MVPA was associated with a lower mortality (HRs: 0.94; 0.85, 1.04 and 0.88; 0.79, 0.98). In joint analysis, a lower mortality from higher volume-adjusted MVPA was only observed for the middle tertile of physical activity volume.The total volume of physical activity was associated with a lower risk of mortality to a greater extent than the contribution of MVPA to physical activity volume. Integrating any intensity of physical activity into daily life may lower mortality risk in middle-aged and older adults, with a small added benefit if the same amount of activity is performed with a higher intensity.