Introduction: Incorporating consumers’ perspectives into the quality of mental health service measurement is a growing priority among mental health professionals’ and policymakers. Despite this, there is limited empirical evidence related to consumer perspectives of quality of mental health services. This study, therefore, aims to measure the mediation and moderation effects of health system structure and process on mental health quality in Ghana. Methods: A random sample of 510 consumers were recruited to complete the Verona Satisfaction Scale (54-items), together with the WHO Disability Assessment Instrument (36 items) using the Redcap application. Confirmatory factor analysis (CFA) and Structural Equation Modelling were used to test the hypothesised theory using STATA 15. Results: The CFA showed that the hypothesised model had a good fit to the data. The findings confirmed the hypothesis that the process constructs mediate the relationship between the health system structure and the outcome of mental health services. Specifically, the health system structure had a positive and significant causal relationship with the mediator-process (β = 0.60; p<0.01) and outcome (β = 0.47; p<0.01). Additionally, the mediator-process had a positive causal relationship with the outcome of the mental health services (β = 0.32; p<0.01). Insurance status (β = 0.07; p>0.05) and type of services (β = 0.025; p>0.05) had a positive moderating effect on the relationship between health system structure and outcome but were not significant. Conclusion: Improvements to mental health system structure and the process could promote the quality of services as experienced by consumers. Government stakeholders are encouraged to accordingly strengthen health systems with the aim of improving the mental health outcomes for consumers.