Neutrophils, which originate from the bone marrow and are characterized by a segmented nucleus and a brief lifespan, have a crucial role in the body's defense against infections and acute inflammation. Recent research has uncovered the complex roles of neutrophils as regulators in tumorigenesis, during which neutrophils exhibit a dualistic nature that promotes or inhibits tumor progression. This adaptability is pivotal within the tumor microenvironment (TME). In this review, we provide a comprehensive characterization of neutrophil plasticity and heterogeneity, aiming to illuminate current research findings and discuss potential therapeutic avenues. By delineating the intricate interplay of neutrophils in the TME, this review further underscores the urgent need to understand the dual functions of neutrophils with particular emphasis on the anti-tumor effects to facilitate the development of effective therapeutic strategies against cancer.