Depression is a common psychological disease, which has become one of the main factors affecting human health. It has a serious impact on individuals, families, and society. With the prevalence of COVID-19, the incidence of depression has further increased worldwide. It has been confirmed that probiotics play a role in preventing and treating depression. Especially,Bifidobacteriumis the most widely used probiotic and has positive effects on the treatment of depression. The mechanisms underlying its antidepressant effects might include anti-inflammation and regulation of tryptophan metabolism, 5-hydroxytryptamine synthesis, and the hypothalamus-pituitary–adrenal axis. In this mini-review, the relationship betweenBifidobacteriumand depression was summarized. It is hoped thatBifidobacterium-related preparations would play a positive role in the prevention and treatment of depression in the future.