Background <p>Profiling disability and mortality risks in older adulthood is essential for government planning, resource allocation, and care services provision. This study showed trajectory of disability and mortality risks using objective measures derived from administrative long-term care insurance (LTCI) claims data in Japan.</p> Methods <p>This cohort study used longitudinal data from LTCI claims, linked with death certificates, and supplemented with population data for non-LTCI eligible individuals, from 2006 to 2018. The dataset comprised 30,347,066 older adults’ records aged 65–94 eligible for LTCI within 1912–1951 birth cohorts (7,221,142 unique individuals). The definition of disability was based on LTCI claims data, quantified by standard hours of care. One-year interval transition probabilities of disability and mortality, categorized by age, sex, and care demanded level, were estimated using a first-order Markov chain.</p> Results <p>The participants had a mean age of 83.8 years (SD = 6.8), with 69.5% being female. Eligibility rates sharply increased in the mid-70s, reaching at 66.8% (81.1%) at 94 years of age for males (females). Probabilities of transitioning to no-disability were almost zero, while maintaining the same level of care showed notably high probabilities, ranging from 60.3% to 99.2% across all ages, sexes, and current care levels. Transition from light-cognitive to heavy-cognitive status ranged between 19.1% and 24.5%. Monte Carlo simulations demonstrated almost perfect predictability of disability and mortality risks in older adults, with maximum difference, 3.2 (2.6) ppt for disability (mortality).</p> Conclusions <p>Care service demand proves mostly irreversible. Measures should focus on preventing worsening disability levels in older adults without disabilities or with only light disabilities, with particular emphasis on preventing cognitive impairment.</p>