Post-translational modifications (PTMs) have become pivotal regulators of protein functionality, serving as dynamic molecular switches that translate genetic information into adaptive plant phenotypes. Through precise and reversible alterations in protein activity, stability, subcellular localization, and interaction networks, PTMs (i.e., phosphorylation, ubiquitination, acetylation, glycosylation, and redox-mediated modifications) coordinate a wide spectrum of biological processes, such as growth and development, stress resilience, nutrient-use efficiency, and immune regulation. This multilayered regulatory capacity confers exceptional plasticity to plant systems, enabling rapid, finely tuned responses to ever-changing environmental cues. Recent advances in proteomics, high-resolution mass spectrometry, and computational biology have substantially deepened our understanding of PTM landscapes in crop plants, uncovering extensive crosstalk between PTMs and other regulatory layers of gene expression. The integration of PTM-centric proteomics with genomics, transcriptomics, and metabolomics has enabled the identification of key regulatory nodes that bridge genotype and phenotype. These insights are increasingly being translated into practical applications, including precision breeding, genome editing, and metabolic engineering, to improve crop resilience and productivity while maintaining yield stability. This chapter integrates current insights into the mechanistic roles of PTMs in controlling plant stress responses, developmental processes, and nutrient acquisition. It further emphasizes emerging multi-omics and genome-editing strategies that strategically target PTM-regulated pathways to develop climate-resilient, high-performing crop varieties. Therefore, the chapter highlights the transformative potential of PTM-informed approaches in driving sustainable agricultural innovation and strengthening global food security.