This study investigates the effects of phased retirement on vitality and how this effect differs for workers dealing with work, family and health strain and low levels of baseline vitality. We used two waves of the NIDI Pension Panel Survey, conducted in 2015 and 2018, in the Netherlands. Data from 1,247 older workers, of whom 10% opted for phased retirement, were analyzed. Vitality is assessed in three ways: a composite measure of vitality, and its subcomponents energy and fatigue. Conditional change regression models demonstrated that transitioning into phased retirement improved vitality and energy levels and reduced fatigue. Older workers with low energy levels at baseline showed greater improvements in energy after using phased retirement: this result was not evident for those with low vitality and high fatigue at baseline. Phased retirement improved vitality for workers with high work strain. Vitality for workers with family or health strain was not improved. Interestingly, the positive effects of phased retirement were equally visible among workers with and without adverse health conditions and caregiving responsibilities. Our study provides evidence on the benefits of phased retirement as a method to sustainably ensure healthy aging of not only vulnerable but all older workers.