["Scandinavian Journal of Psychology, EarlyView. ", "\nABSTRACT\nThis study investigated frontal quantitative electroencephalogram (QEEG) biomarkers of cognitive dysfunction in unipolar depression (UD). Our primary aims were to: (1) find the difference between healthy controls and unipolar depression in NPA, (2) explore age/sex effects, (3) investigate how working memory interacts with other neurocognitive domains, (4) investigate the relationship between verbal fluency and cognitive performance in unipolar depression, and (5) characterize frontal QEEG–cognition relationships. We examined 71 UD patients (median age: 51; range: 38–67) who met DSM‐5 criteria for unipolar depression via the Structured Clinical Interview for unipolar depressive disorder diagnoses (SCID‐I) and 29 statistically similar sex‐age healthy controls (median age: 45; range: 34–69) using neuropsychological assessments (NPA) and QEEG. Results revealed significant differences in almost all of the NPA domains in UD patients compared to healthy controls. Age negatively correlated with simple attention, working memory, and verbal delayed recognition, while positively correlating with verbal memory false recognition errors, suggesting older participants were more susceptible to memory errors. In the group of UD patients, women were older than men, and men had higher levels of education (p < 0.01). The females performed worse in working memory, facial recognition, simple attention, and complex attention (p < 0.05). Working memory was a central impairment, strongly connected to problems in verbal fluency and long‐term memory. Frontal QEEG power bands (delta, theta, and beta) were significant biomarkers for domain‐specific cognitive deficits in depression. These findings highlighted QEEG's potential for objectively assessing cognitive impairment in UD and personalizing interventions.\n"]