Childhood psychological maltreatment has a significant impact on family-related factors and adult mental health, emphasizing the importance of investigating its effects and developing appropriate interventions. Loneliness is also an important factor that needs further exploration in relation to these variables. This study aims to gain a better understanding of the relationship between these variables and to examine the role of family belongingness, family sense of coherence, and loneliness as chain mediators between childhood psychological maltreatment and adult mental well-being. Data from 369 participants residing in 46 different cities in Turkey were analyzed. The participants were selected to represent a diverse range of backgrounds and living conditions, predominantly female (n = 282, 76.4%) and well educated (n = 300, 81.3%). A structural mediation model was used to analyze the data. The variables of childhood psychological maltreatment, family belongingness, family sense of coherence, loneliness, and adult mental well-being were measured and examined for their relationships. The findings of the study indicated that family belongingness, family sense of coherence, and loneliness mediate the association between childhood psychological maltreatment and adult mental well-being. Childhood psychological maltreatment poses a risk to a positive family sense of coherence and family belongingness, while loneliness emerges as a significant factor affecting adult mental well-being. These findings highlight the importance of addressing childhood maltreatment and promoting family support and coherence to enhance mental well-being in adulthood. Further research and interventions in this area are warranted.