Secondary metabolites, also known as the specialized metabolites, are bioactive small molecules produced by plants that play important roles in growth, development, defense, and environmental adaptation. Vegetables synthesize a diverse array of specialized metabolites, including phenolics, terpenoids, alkaloids, and sulfur compounds, which contribute to their nutritional values, flavors, and aromas. The biosynthesis of these phytochemicals is tightly regulated by complex mechanisms at multiple levels. Environmental stimuli and developmental signals trigger cascades affecting the epigenetic landscapes, transcriptional circuits, and posttranslational modifications. These changes orchestrate coordinated expression of genes encoding specialized metabolic enzymes, transporters, and regulators. At the epigenetic level, DNA methylation, histone modifications, chromatin architecture, and non-coding RNAs modulate the transcriptional accessibility of clustered biosynthetic genes. Transcription factors, especially MYB, bHLH, WRKY, and AP2/ERF families, form intricate circuits with phytohormones to control spatial and temporal expression of the pathway genes. Posttranslational mechanisms like phosphorylation modulate activities of metabolic enzymes and regulators in response to cellular signals. Together, this multi-level regulatory network provides plants with precise control over specialized metabolism, allowing plant adaptation to changing environments. A deeper understanding of the complex regulation of vegetable specialized metabolites will facilitate phytochemical enhancement for improving human health, crop resilience, and agricultural sustainability.