Adults with cognitive impairment are prone to living alone in large numbers but receive relatively little attention. This study aimed to evaluate whether living alone with cognitive impairment was associated with a higher burden of functional disability but lack of informal care. 982 observations of adults living alone with cognitive impairment and 50,695 observations of adults living with others and with normal cognition were identified from 4 waves (2011/2012, 2013, 2015, and 2018) of the China Health and Retirement Longitudinal Study (CHARLS). A matched comparator was selected using propensity score matching (1:2). Functional disability included disability in Activities of Daily Living (ADL), Instrumental Activities of Daily Living (IADL), and mobility. The time of receiving informal care was measured in monthly hours. Adults living alone with cognitive impairment demonstrated significantly higher odds ratio of ADL disability (OR = 1.59, 95 % CI: 1.30, 1.95), IADL disability (OR = 1.19, 95 % CI: 1.00, 1.44), mobility disability (OR = 1.38, 95 % CI: 1.12, 1.70), but received fewer hours of informal care (β = −127.7 h per month, standard error = 25.83, P < 0.001), compared to the adults living with others and with normal cognition. This study highlights the high burden of functional disability but low coverage of informal care among Chinese adults living alone with cognitive impairment and calls for more resources to be allocated to this vulnerable subpopulation to improve the functional health and to increase the provision of long-term care services. •Unique social-demographic features of adults living alone with cognitive impairment.•This vulnerable group experiences severe burden of functional disability.•Informal care coverage for such group in the community is low.•Propensity score matching is used to address the confounders and data imbalance.