Abstract Background Pemphigus is a group of autoimmune blistering disorders that have been associated with dementia in previous studies. Mild cognitive impairment (MCI) can be the first stage of progression into dementia. The objective of the present study was to evaluate the frequency of MCI in pemphigus patients compared to a control group. Methods This case‐control study included 80 patients with pemphigus referred to the dermatology clinics of Shohadaye Tajrish and Loghman Hakim hospitals, Tehran, Iran, in 2021. A group of 80 individuals without pemphigus who visited the same clinics for cosmetic consultation or interventions were regarded as controls. Age, sex, marital status, and education were recorded for all participants. Disease duration, medications, and severity were noted for pemphigus patients. The Persian version of the Montreal Cognitive Assessment (MoCA) test was used to assess cognitive function. Results MCI was significantly more frequent in pemphigus patients than in controls (55% vs. 37.5%, P = 0.026). Furthermore, the total MoCA score was significantly lower in pemphigus patients compared to controls (23.98 ± 3.77 vs. 25.21 ± 3.45, P = 0.032); however, among MoCA's different domains, only the executive functions score was significantly lower in pemphigus patients ( P = 0.010). After adjustment, multivariable logistic regression analysis revealed that every 1‐year higher education in patients decreased the odds of MCI by 52% (adjusted odds ratio = 0.483, 95% confidence interval 0.326; 0.715, P < 0.001). Conclusions The frequency of MCI was found to be significantly higher, and overall scores of the MoCA test, as well as its executive function domain, were significantly lower among pemphigus patients in this study compared to the control group. Additionally, a higher level of education was associated with decreased odds of MCI in pemphigus patients. Identifying pemphigus patients with MCI through the use of the MoCA test can facilitate early intervention, enabling them to seek help and support.