To determine whether there are differences in the health-related quality of life (HRQOL) of older adult survivors of breast cancer (BC) diagnosed in different time periods and to gain insight into whether advances in BC treatment have improved HRQOL. Three cohorts of older adult survivors of BC diagnosed before 1995, from 1996 to 2005, and from 2006 to 2015 were examined using the Surveillance, Epidemiology, and End Results-Medicare Health Outcomes Survey linked databases. HRQOL was measured using the Veterans RAND 12-Item Health Survey. Mean cohort HRQOL scores were compared using analysis of variance, then multivariate regression models were used to examine the effects of cohort membership and covariates on mental and physical HRQOL. Adjusted mean HRQOL scores trended significantly lower with each successive cohort. Higher comorbidity count and increased functional limitations were negatively associated with HRQOL, and income, education level, and better general health perceptions were positively associated with HRQOL. Regardless of time since diagnosis, older survivors of BC are at risk for poor HRQOL and should be regularly assessed. Maximizing HRQOL requires consideration of the survivor's resources, comorbidities, and functional limitations when planning care.