Nicotine-degrading microorganisms (NDMs) are a special microbial group which can use nicotine as the sole carbon and nitrogen source for growth. Since the 1950s, the bioconversion of nicotine by microbes has received increasing attention, and several NDMs have been identified, such as Arthrobacter nicotinovorans, Microsporum gypseum, Pellicularia filamentosa JTS-208, and Pseudomonas sp. 41. In recent years, increasing numbers of NDMs have been isolated and identified from tobacco plantation soil, leaf, and tobacco waste. Meanwhile, the metabolic pathway and degradation mechanism of nicotine have been elucidated in several NDMs, such as A. nicotinovorans, Agrobacterium tumefaciens S33, Aspergillus oryzae, and Pseudomonas putida S16. Moreover, several NDMs have been used in improving the quality of cigarettes, treating tobacco waste, and producing valuable intermediates of nicotine. Here, we summarize the diversity, phylogenetic analysis, and potential applications of NDMs.