Citrobacter species are increasingly recognised as significant opportunistic pathogens within the Enterobacteriaceae family, capable of causing a variety of infections, including urinary tract infections, sepsis, and neonatal meningitis. Their clinical relevance has been magnified by the rapid emergence of multidrug-resistance, particularly due to the acquisition of extended-spectrum β-lactamases and carbapenemases. Across regions, Citrobacter spp. including C. koseri implicated in severe neonatal central nervous system infection are increasingly recognised in healthcare-associated infections, while rising multidrug-resistance and carbapenemase production add to the global AMR burden. Traditional phenotypic methods often fall short in distinguishing closely related Citrobacter species, necessitating the integration of advanced genotypic techniques such as PCR, MLST, and whole-genome sequencing. This narrative review explores the phenotypic and genotypic characteristics of Citrobacter species, their role in human disease, and the mechanisms underlying their antimicrobial resistance. The review emphasises the importance of precise identification and molecular characterisation in guiding clinical management and informing public health interventions.