Abstract: Biological nitrogen removal processes in wastewater treatment frequently encounter engineering bottlenecks such as slow start-up periods and high susceptibility to environmental stresses.Quorum sensing (QS),a regulatory mechanism by which microorganisms exchange information through signaling molecules and coordinate collective behaviors, has emerged as a promising approach for enhancing nitrogen removal. This paper systematically reviews the application status of N-acyl homoserine lactones (AHLs)-mediated QS in partial nitrification-denitrification and anaerobic ammonium oxidation (anammox) processes. The underlying regulatory mechanisms are profoundly analyzed: accelerating sludge granulation and biofilm formation by promoting the secretion of extracellular polymeric substances (EPS) ; driving the enrichment and succession of functional nitrogen-removing microbial communities ; and precisely regulating the expression of nitrogen metabolism-related functional genes and key enzyme activities at the cellular metabolic level. Addressing the limitations in translating current laboratory-scale research into practical engineering applications, future prospects are proposed, including the development of low-cost inducers to enhance endogenous secretion, the exploration of complex QS systems under complicated habitats, and the application of multi-omics combined analysis. This review aims to provide theoretical support for the development of stable and highly efficient novel biological nitrogen removal technologies.