Background In many communities around the world, informal caregivers of older adults with mental disorders (such as dementia) represent an essential, yet often underappreciated, source of long-term care. The present study aimed to determine the personal experiences of such caregivers, which could be instrumental for developing means of improving the quality of care for both care receivers and their informal caregivers.Methods Five semi-structured focus-group discussions were held. The participants (n = 31) were all informal caregivers of older adults with mental disorders. The focus-group discussions were audio-recorded and transcribed verbatim. An inductive approach was used, and thematic data analysis was applied.Results Four thematic categories were identified: learning caregiving through personal experience; implications of caregiving on social wellbeing; caregivers’ contradictory emotions regarding care delivery; and addressing challenges regarding care provision.Conclusions This study revealed, among the informal caregivers, a variety of experiences, contradicting feelings, and problem-solving strategies relating to the care of older adults with mental disorders. Becoming an effective caregiver involves professional and psychological development, but also requires a relevant educational background, a positive attitude, and a supportive environment. Caregiving largely impacts the emotional, physical, and social wellbeing of the person; thus, comprehensive approaches are needed to prevent burnout and associated social disadvantages.