<p>The fabrication of nanoparticles (NPs) via eco-friendly methods has gained attention due to its sustainability, accessibility, and affordability. The current work aimed to establish a comparative study between the chemical and phytosynthesis of silver nanoparticles using the extract of <i>Ceratophyllum demersum</i> (Coontail), a submerged aquatic plant species from Egypt, using five volume ratios of the aqueous plant extract (1&#xa0;mL, 2.5&#xa0;mL, 5&#xa0;mL, 10&#xa0;mL, and 20&#xa0;mL). The morphological and compositional properties of both phyto- and chemosynthesized NPs were performed. Electron microscopy imaging showed that the AgNPs’ sizes decreased, and their shapes were more distinct and well-defined as the volume of plant extract increased. The FTIR elucidated the strategies of NP phytopreparation and stabilization of NPs through conjugation to flavonoid compounds in the extract. The zeta potential validates that the FTIR analysis shows that the plant extract can bio-stabilize the produced AgNPs via OH, C–O, and C = N bonds. The XRD data showed that the phyto- and chemo-AgNPs had face-centered cubic crystalline NPs. The antimicrobial potential of the synthesized NPs against seven human pathogenic bacteria demonstrated that the phyto-NPs had a superior bacterial inhibitory capacity than the chemosynthesized ones, especially against the Gram-negative bacteria more than Gram-positive ones. The antioxidant capacity of all synthesized AgNPs was synergistic, but the highest was that of AgNPs made using 20&#xa0;mL of extract. In conclusion, <i>Ceratophyllum demersum</i> proved its efficiency as a bioactive compound to fabricate AgNPs employing five various ratios of the plant extract for developing novel therapeutics to combat biological problems with minimal side influences.</p> Graphical Abstract <p>Graphical abstract represents the biosynthesis of AgNPs using Ceratophyllum demersum leaf extract.</p> <p></p>