People with multiple sclerosis (PwMS) often experience cognitive impairments that affect independence in their activities. Transcranial direct current stimulation (tDCS) has been recently used for treating cognitive impairments in patients with neurological conditions. This review aims to investigate the effects of tDCS on cognitive function in PwMS. Databases including "PubMed, SCOPUS, MEDLINE, EMBASEe, and Web of Science" were searched until July 2024. The risk of bias was evaluated using the Cochrane Collaboration tool (CCT). Nine were selected for inclusion in this review, encompassing 274 PwMS, 77.74% of whom were females. Five studies have a low risk of bias, while four have a moderate risk of bias on the CCT. The findings revealed mixed evidence regarding the effects of tDCS on cognitive function in PwMS. In conclusion, most studies have shown that tDCS does not improve various cognitive domains in PwMS. However, due to the limited number of studies and their high heterogeneity, further research is needed to assess the immediate and long-term impacts of tDCS on numerous cognitive domains in PwMS, understand the relationship between PwMS characteristics and their response to the tDCS intervention, and define the optimal tDCS treatment protocols for treating cognitive impairments in PwMS.