This review explores the intricate relationship between human milk oligosaccharides (HMOs) and the gut microbiota, particularly focusing on bifidobacteria. HMOs, complex and diverse glycans present in human breast milk, resist gastrointestinal digestion and provide numerous benefits to the developing infant. Certain bifidobacterial species, among the earliest colonizers of breastfed infants, have adapted to metabolize various HMO structures. These infant-associated bifidobacteria possess enzymes and transporters that facilitate HMO uptake and metabolism, contributing to the establishment and persistence of a healthy gut microbiota. The review discusses the structural diversity of HMOs, their variation in composition and concentration, and the factors influencing these variations. It also delves into the mechanisms by which infant-associated bifidobacteria utilize HMOs, including intracellular and extracellular strategies. The impact of HMOs on the infant gut microbiota, including the modulation of microbial composition and the production of beneficial metabolites, is highlighted. Additionally, the review examines the role of HMOs in shaping the infant gut microbiota and the potential of HMOs in modulating gut health.This review explores the intricate relationship between human milk oligosaccharides (HMOs) and the gut microbiota, particularly focusing on bifidobacteria. HMOs, complex and diverse glycans present in human breast milk, resist gastrointestinal digestion and provide numerous benefits to the developing infant. Certain bifidobacterial species, among the earliest colonizers of breastfed infants, have adapted to metabolize various HMO structures. These infant-associated bifidobacteria possess enzymes and transporters that facilitate HMO uptake and metabolism, contributing to the establishment and persistence of a healthy gut microbiota. The review discusses the structural diversity of HMOs, their variation in composition and concentration, and the factors influencing these variations. It also delves into the mechanisms by which infant-associated bifidobacteria utilize HMOs, including intracellular and extracellular strategies. The impact of HMOs on the infant gut microbiota, including the modulation of microbial composition and the production of beneficial metabolites, is highlighted. Additionally, the review examines the role of HMOs in shaping the infant gut microbiota and the potential of HMOs in modulating gut health.