Quorum sensing (QS) coordinates microbial behavior and metabolic interactions in response to environmental cues, yet its role in the microbial attenuation of marine lipophilic phycotoxins remains largely unresolved. Here, we enriched functional marine microbial consortia under nutrient-limited conditions using the lipophilic polycyclic polyether neurotoxins gambierone and 44-methylgambierone as sole carbon sources. Amplicon and metagenomic profiling showed that exposure to these toxins drove community specialization and was accompanied by enrichment of genes associated with QS signal biosynthesis and perception. From these consortia, we isolated five core bacterial degraders, among which several strains removed nearly 80% of both toxins within five days. In the most efficient degrader, Vibrio coralliilyticus, deletion of the autoinducer synthase gene luxS reduced toxin degradation by up to 51.91%, whereas genetic complementation largely restored this phenotype. Comparative transcriptomics indicated that luxS-dependent degradation was linked to branched-chain amino acid-associated decarboxylative metabolism. By contrast, loss of luxS redirected cellular metabolism toward a methylcitrate cycle-dominated state and induced a secretory phenotype associated with competition and virulence. Together, our findings identify QS as a key regulator of phycotoxin biodegradation and reveal a metabolic mechanism by which autoinducer signaling shapes the fate of complex marine toxins. This work provides a mechanistic basis for understanding microbial detoxification processes in marine ecosystems and highlights QS signaling as a potential target for mitigating phycotoxin contamination.