Caring for someone with Bipolar disorder (BD) is unique, and the severity and complexity of symptoms can overwhelm informal carers such as family, friends, and partners. This study employed a concurrent mixed-methods model to investigate the lived experience of informal carers caring for those with BD in Australia. Participants (n = 46) answered an online survey containing standardised measures of quality of life and coping mechanisms as well as open-ended questions about their caring role challenges and support. Carers reported mental health problems as the highest care-related burden and reported low perceived social support. However, a one-way MANOVA indicated no difference in these dimensions between carers of people with BD I and II. Reflexive thematic analysis revealed five superordinate themes relating to informal caregivers' challenges, coping strategies, and the support they need. The themes were: like a roller-coaster; carer mental health; complexities of the carer role and diagnosis; how to cope; and multifaceted support. The oscillation of symptoms and complexities of the caring role increased the burden on carers and created mental health challenges, requiring carers to use various coping strategies. Findings highlight the need for individualised, multimodal support for carers. Carers need adequate and accessible support through strong partnerships with healthcare providers to improve their own quality of life and mental health and, in turn, those in their care.