Background: Cognitive impairment and reduced health-related quality of life (HRQoL) are well-established sequelae of critical illness. Studies on survivors of critical illness have found delirium to be a predictor of these conditions, but evidence regarding survivors of acute brain injury is sparse. We aimed to explore if delirium duration was associated with 1-year cognitive impairment and reduced HRQoL in patients with acute brain injury. Method: Intensive care unit (ICU) delirium was assessed using the Intensive Care Delirium Screening Checklist. Cognitive status was assessed using the Repeatable Battery for Neuropsychological Status (RBANS) and HRQoL using the European Quality of Life 5-dimension questionnaire (EQ-5D). We used a multiple linear regression for testing the association of delirium duration with cognitive impairment and quality of life, respectively. Results: Forty-seven survivors of acute brain injury participated in follow-up and 35 completed RBANS. Delirium was present in 39 of 47 (83%) with a median duration of 4 days. Delirium duration did not predict cognitive impairment (95% CI −4.1 to 0.5) or lower HRQoL (95% CI −1.4 to 2.7). Moderate-to-severe cognitive impairment was present in 17 of 35 (49%) participants, and they had a mean EQ-5D health visual analogue scale of 70.9 vs 81.6 for the Danish age-matched norm. Conclusions: Our sample did not demonstrate an association between delirium and 1-year cognitive impairment or reduced HRQoL. Still, a large proportion of the participants were cognitively impaired, and their quality of life was lower compared to norm. Larger studies are necessary to explore these associations further.