: To identify joint trajectories of physical frailty and cognitive impairment among community-dwelling older adults and to determine modifiable factors for each trajectory. : Data were utilized from the Korean Longitudinal Study of Aging, which was conducted between 2006 and 2018. Physical frailty was assessed using the Fried phenotype, and cognitive impairment was evaluated using the Korean version of the Mini-Mental State Examination. Group-based trajectory modeling and logistic regression were employed for the analyses. : Based on longitudinal data, 415 participants averaging 72.2 years of age were analyzed. Three trajectories of physical frailty were identified: mild physical frailty, moderate physical frailty, and improving frailty. Two trajectories of cognitive impairment were identified: stable cognitive impairment and improving cognitive impairment. Factors influencing physical frailty trajectories included the number of medications taken, being overweight or obese, and depression. Education level was found to be associated with cognitive impairment trajectories. : This study provides evidence for the distinct identification of joint trajectories of physical frailty and cognitive impairment, which can inform the target groups for intervention. It offers a basis for including modifiable physical and mental factors in intervention components for physical frailty trajectories.