<p>Numerous studies have shown the advantageous effects of silicon in reducing the harmful salt-induced effects in plants. However, the underlying mechanisms linked to oxidative stress, specifically the implication of silicon in improving secondary metabolism, are yet to be studied and discussed. This study evaluated silicon’s effect on the defensive antioxidant systems, most importantly on the secondary metabolism in salt stressed <i>Sorghum bicolor</i>. Plants were treated with 150 mM NaCl in the presence or absence of 0.5 mM silicon (Na₂SiO₃). Growth parameters, enzymatic and non-enzymatic antioxidant evaluations, as well as HPLC analysis of leaf phenolic profile were studied. Salinity stress significantly reduced plant growth and altered most of the studied biochemical and physiological parameters, mainly due to the increase of oxidative stress. The supply of silicon enhanced biomass production, stimulated chlorophyll and carotenoid contents, decreased oxidative stress markers accumulation (hydrogen peroxide (H₂O₂) and malondialdehyde (MDA)), and adjusted enzymatic antioxidants to plant requirements. Notably, silicon stimulated the contents of leaf phenolics, flavonoids, and condensed tannins, and also enhanced Total Antioxidant Activity (TAA), DPPH scavenging ability, and Ferric Reducing Antioxidant Power (FRAP). Quantitatively, salt stress affected all phenolic acids and flavonoids identified in leaves of <i>Sorghum bicolor</i>, with no qualitative difference compared to control. The supply of silicon enhanced the contents of most revealed components, but also with no qualitative modifications. Additionally, silicon decreased the contents of rutin and quercetin. In conclusion,&#xa0;silicon enhanced <i>Sorghum bicolor</i> tolerance to salt stress, mainly throughout stimulating its secondary antioxidant defense system. Our results confirmed that silicon supply significantly reduces the degree of oxidative damage in <i>S. bicolor</i> plants.</p>