Although cell wall polymers play important roles in the tolerance of plants to abiotic stress, the effects of salinity on cell wall composition and metabolism in grasses remain largely unexplored. Here, we conducted an in-depth study of changes in cell wall composition and phenolic metabolism induced upon salinity in maize seedlings and plants. Cell wall characterization revealed that salt stress modulated the deposition of cellulose, matrix polysaccharides and lignin. The extraction and analysis of arabinoxylans by size-exclusion chromatography, two-dimensional NMR spectroscopy and carbohydrate gel electrophoresis showed a reduction of arabinoxylan content in salt-stressed roots, with no changes in xylose/arabinose ratios. Saponification and mild acid hydrolysis followed by RP-HPLC analysis revealed that salt stress also reduced the feruloylation of arabinoxylans. Determination of lignin content and composition by nitrobenzene oxidation and two-dimensional NMR confirmed the increased incorporation of syringyl units in lignin polymer. Our data also revealed the induction of the expression of genes and enzymes enrolled in phenylpropanoid biosynthesis under salinity. The UPLC-MS-based metabolite profiling confirmed the modulation of phenolic profiling by salinity and the accumulation of ferulate and its derivatives 3- and 4-O-feruloyl quinate. In conclusion, we present a model for explaining cell wall remodeling in response to salinity.