Population-based studies indicate that psoriasis associates a greater risk of comorbidities that alter mood, such as anxiety and, above all, depression. We applied a complete panel of validated questionnaires to perform a full psychopathological exploration according to the DSM-V classification of psychiatric diseases in 300 psoriatic patients. A dose-response association with depression and anxiety (the more severe psoriatic patients have more risk of having depression or anxiety) was observed. The Montgomery-Asberg Depression Rating, Hamilton Rating for Depression, Hospital Anxiety and Depression scales (for depression), and State Anxiety Inventory (for anxiety) seem to better detect such mood comorbidities in psoriatic patients. Psoriasis is a chronic skin disease associated with considerable physical and psychological comorbidities. Stress and emotional disturbances have been implicated in both triggering the onset and exacerbation of psoriasis. In order to determine the level of perceived stress and mood alterations in patients with psoriasis and their association with disease severity, 300 individuals completed diverse validated questionnaires assessing stress and psychological mood. Evaluation of perception of disease was also measured. A significant association between psoriasis severity and mood, emotional disturbances and an impact on assessments of the quality of life were observed. Particularly, Montgomery-Asberg Depression Rating Scale, Hamilton Rating Scale and Hospital Anxiety and Depression Scale for Depression detected a significant risk for depression in relation to the disease severity. The association between depression features, anxiety and perceived stress with psoriasis severity is important and can influence the appropriate management of psoriasis.