Background: Mental illness, such as depression, anxiety disorders, attention deficit hyperactivity disorder and different addictive diseases, has increased among young adults over the last decade. Mental illness is associated with distress and problems functioning in social activities. Healthcare centres, that is, primary care, serve as the first point of contact with healthcare professionals for those young adults and provide outpatient medical and nursing care covering both physical and mental illness. Objective: To explore experiences of primary care among young adults with mental illness. Methods: A systematic literature review was conducted that followed the method of Bettany–Saltikov and McSherry. A keyword search was performed in various databases, and after a quality assessment 23 articles were included in the review. Results: Young adults' experiences from primary care are described in four categories – Facing difficulties to accept help, relational preconditions, structural and organisational hindrances and satisfaction with youth-focused mental health interventions. Young adults with mental illness experience many difficulties in accessing and receiving proper help from primary care. Further, they did not believe in recovery from mental illness, and they also expressed a lack of mental health literacy. Conclusion: While being the first contact with healthcare professionals, primary care needs to adjust its services to address the growing group of young adults suffering from mental illness. It is necessary to provide tailored guidelines and interventions in primary care for young adults with mental illness, and the Tidal Model may improve the contacts with young adults in primary care.