OBJECTIVE: Intellectual disability liaison nurses in general hospitals could enhance access to high-quality, adapted healthcare and improve outcomes. We aimed to explore associations between the input of intellectual disability liaison nurses and the quality of care in people with intellectual disability who are admitted to hospital. DESIGN: Retrospective analysis of a national dataset of mortality reviews. SETTING: General hospitals in England. PARTICIPANTS: 4742 adults with intellectual disability who died in hospital between 2016 and 2021 and whose deaths were reviewed as part of the Learning from Lives and Deaths mortality review programme. OUTCOME MEASURES: We used logistic regression to compare the sociodemographic and clinical characteristics of those who did, and did not, receive input from an intellectual disability liaison nurse. We explored associations between liaison nurse input, care processes and overall quality of care. RESULTS: One-third of people with intellectual disability who died in hospital in England between 2016 and 2021 had input from an intellectual disability liaison nurse. Intellectual disability liaison nurse input was not evenly distributed across England and was more common in those who died of cancer. Having an intellectual disability liaison nurse involved in an individual's care was associated with increased likelihood of reasonable adjustments being made to care (adjusted OR (aOR) 1.95, 95% CI 1.63 to 2.32) and of best practice being identified (aOR 1.37, 95% CI 1.17 to 1.60) but was not associated with a rating of overall quality of care received (aOR 0.94, 95% CI 0.78 to 1.12). CONCLUSIONS: Intellectual disability liaison nurses see only a minority of people with intellectual disability who are admitted to hospital in England. Increasing the availability of intellectual disability liaison nurses could improve care for this disadvantaged group.