BACKGROUND: The trajectory of frailty and intrinsic capacity (IC) often overlap in older adults. Longitudinal analyses of transitions of frailty and IC, and their associations with incident functional decline are limited. The present study aimed to identify transitions of frailty status and IC, and explore associations between transitions of frailty and IC, and future disability among community-dwelling older adults. METHODS: In the West China and Aging Trend Study, 808 participants aged ≥ 60 years completed baseline and three years follow-up (frailty, IC and disability assessments). Physical frailty was measured based on Fried phenotype. IC was evaluated by five domains (cognition, locomotion, sensory, psychological, and vitality). Disability was defined as a need for assistance in any items in activity of daily living (ADL) or the instrumental activity of daily living (IADL). Logistic regressions were performed to examine their relationships. RESULTS: Four transitions of IC status (kept well: 27.4%, improved: 8.4%, worsened: 35.4%, and kept poor: 28.8%), and two transitions of frailty status (kept not-frail/improved: 93.2%, kept frail/worsened: 6.8%) were identified. Impaired locomotion and vitality at baseline were significantly associated with kept frail or worsened frail. However, impaired sensory and vitality at baseline not frailty status was significantly associated with transitions of IC. Adjusted for covariates and transitions of frailty, kept poor IC was associated with ADL (OR = 2.26, 95%CI = 1.17,4.34) and IADL disability (OR = 3.74, 95%CI = 1.79, 7.82). CONCLUSIONS: Transitions of IC, but not frailty were associated with higher risk of incident disability. Baseline locomotion and vitality impairment were associated with worsened or kept frail. Our findings support the WHO's notion of monitoring and optimizing IC to delay deterioration of IC and preventing frailty and disability. CLINICAL TRIAL NUMBER: ChiCTR1800018895.