With society’s growing diversity, it is increasingly crucial to comprehend the care needs of older migrants with dementia and their informal carers. This study explores the experiences of informal carers of older migrants with dementia using professional care, focusing on the participants’ perceptions of whether the delivered professional care meets the needs of the informal carer and their family member with dementia. Purposive sampling identified 17 informal carers living in Belgium and caring for older first-generation labour migrants from Italian and Turkish backgrounds. In-depth interviews were conducted and inductive data were analysed using the Qualitative Analysis Guide of Leuven, a method inspired by the constant comparative method. The findings are presented through composite narrative vignettes. The data analysis revealed six predominant themes: (1) Informal carers are hoping for engagement from professional care providers, to create together a care alliance for the older person with dementia; (2) Informal carers experience cold substandard care provision from professional care providers towards their loved ones; (3) Informal carers need to feel a sense of home to be able to trust the professional care providers; (4) Informal carers experience culturally insensitive care practices by professional care providers; (5) Informal carers struggle with the responsibility of informal care-giving in the context of today’s world; (6) Informal carers experience the cumulative mental load of care-giving. Informal carers of older migrants with dementia face a cumulative mental burden through limited adapted-care options, cultural insensitivity in services, care-giving duties and additional tasks to bridge the professional care gaps.