AbstractFrailty refers to a decline in the physiological functioning of one or more organ systems. It remained unclear whether variations in the trajectory of frailty over time were associated with subsequent cognitive change. The aim of the current study was to investigate the association between frailty trajectories and subsequent cognitive decline based on the Health and Retirement Study (HRS). A total of 15,454 participants were included. The frailty trajectory was assessed using the Paulson–Lichtenberg Frailty Index, while the cognitive function was evaluated using the Langa–Weir Classification. Results showed that severe frailty was significantly associated with the subsequent decline in cognitive function (β[95% CI] = −0.21 [−0.40, −0.03],p= 0.03). In the five identified frailty trajectories, participants with mild frailty (inverted U‐shaped,β[95% CI] = −0.22 [−0.43, −0.02],p= 0.04), mild frailty (U‐shaped,β[95% CI] = −0.22 [−0.39, −0.06],p= 0.01), and frailty (β [95% CI] = −0.34 [−0.62, −0.07],p= 0.01) were all significantly associated with the subsequent cognition decline in the elderly. The current study suggested that monitoring and addressing frailty trajectories in older adults may be a critical approach in preventing or mitigating cognitive decline, which had significant implications for healthcare.