Correctional psychology and public health have been increasingly concerned with the mental health and psychological well-being of those who are incarcerated. Numerous psychological stressors, such as loneliness, loss of autonomy, exposure to violence, and disconnection from social support networks, are linked to incarceration. These pressures have a major role in the high rates of mental health conditions like depression, anxiety, PTSD, and substance use disorders that are found in prison populations. This narrative review summarizes the body of research on the mental health issues that prisoners encounter, looking at both institutional and individual factors that affect psychological outcomes while incarcerated. It also looks at how the prison environment, coping mechanisms, and emotional control affect the wellbeing of convicts. Particular focus is placed on how mental illness intersects with pre-incarceration trauma, gender, and race. The evaluation also identifies crucial gaps in care as well as effective methods in the present mental health services provided in correctional settings. The results highlight the necessity of thorough, trauma-informed mental health treatments that go beyond symptom relief to attend to the more extensive social and emotional requirements of those who are incarcerated. Enhancing mental health services in prisons helps inmates' psychological health and aids in their effective rehabilitation and reintegration into society after release. In order to build compassionate and encouraging prison settings, this review highlights the significance of staff training, policy changes, and ongoing research. It also argues for a systemic change in the way mental health is emphasized within correctional facilities.