Maternal mental illness is a major public health issue and can adversely affect the whole family. Increasingly, research and policy are recognising the benefits of a family focused approach to practice, an approach which emphasises the family as the unit of attention. This review was conducted with the aim of systematically analysing the qualitative literature surrounding health visitors’ family focused practice, with mothers who have mental illness and/or substance misuse. Through the synthesis we developed three main findings: 1) parents’ needs regarding health visitors’ family focused practice, 2) the ambiguity of mental illness in health visiting, and 3) the challenges of family focused practice in health visiting. Above all, health visitors, families and mothers with mental illness experience many challenges in family focused practice, even though it is both desirable and beneficial. This calls for a deeper understanding of how family focused practice can be effectively practiced in health visiting.