Acquired brain injury (ABI) is one of the most common causes of disability and death globally. Support from informal caregivers is critical to the wellbeing and quality of life of people with ABI and supports the sustainability of global health and social care systems. This study presents an in-depth qualitative analysis of the experiences of 8 British informal caregivers supporting someone with ABI. Semi-structured interviews were conducted with narratives transcribed verbatim and analysed using Interpretative Phenomenological Analysis (IPA). Three superordinate themes were generated: making sense of brain injury; being consumed by caregiving; and the changing self. These data highlight the impact of caregiving on caregiver’s illness perceptions and sense of self. By identifying negative and positive changes in caregiver’s sense of self, and dilemmas regarding the care recipient’s behaviour, we address less understood aspects of caregiver experiences. Caregiving can pose both challenges to the caregiver’s sense of identity and an opportunity for self-growth. Some caregivers exhibit resilience throughout their journey, with post-traumatic growth more apparent in the later stages of caregiving. Illness perceptions shape caregiver wellbeing and family dynamics, and indicate the need to address stigmatisation and discrimination faced by ABI survivors and caregivers. Although some caregivers acquired positive meaning and enrichment from their caregiving, previously described challenges of ABI caregiving are supported. Overall, our findings support the need for timely psychological/mental health support for caregivers, caregiver education, and the provision of short breaks from caregiving.