Evidence is accumulating for the presence of cognitive impairment in patients with major depressive disorder (MDD). The Prospective Epidemiological Research on Functioning Outcomes Related to Major Depressive Disorder in Japan (PERFORM-J) study is a 6-month, non-interventional, prospective, multicenter, epidemiological study. Using baseline data, the relationship between cognitive symptoms and psychosocial function was analyzed in Japanese patients with MDD.A total of 518 Japanese outpatients (aged 18-65 years) with MDD initiating new antidepressant monotherapy (first-line or switch from a previous drug) participated. Assessment measures were: physician-rated Montgomery-Asberg Depression Rating Scale (MADRS) (depression severity); Digit Symbol Substitution Test (DSST) (objective cognition); and patient-rated Perceived Deficits Questionnaire - Depression (PDQ-D) (subjective cognition); Sheehan Disability Scale (SDS); Work Productivity and Activity Impairment questionnaire (WPAI) (psychosocial function); and EuroQol-5 Dimension-5 Level (quality of life).Over half of patients exhibited a greater than 1 standard deviation decline below norm in objective cognition, as measured by the DSST. Severity of depressive symptoms correlated positively with subjective (PDQ-D), but not objective (DSST) cognition. Depression severity and subjective cognition were significantly associated with psychosocial function, as measured by the SDS and WPAI (except the absenteeism items). Conversely, the association between objective cognition and psychosocial function was not significant.Only outpatients were recruited. Occupations and job-related stress levels were not taken into account.Japanese patients with MDD presented a high incidence of cognitive impairment. The relationships between cognitive and psychosocial function in these patients suggest a need for therapeutics targeting cognitive impairment of MDD.