This paper reports the extraction process of polyphenols from the industrially disposed garlic husk (GH) using different studied solvents (water, methanol, ethanol and 50% aqueous solutions of methanol and ethanol). The highest extraction yield was achieved with water (26.5%) and high bioactive potential was shown by the samples extracted with 50/50 methanol/water (25 mg GAEs/g dry GH, 0.617 mg QE/g dry GH, IC50 = 0.26 mg/mL for DPPH assay, RP0.5AU = 2.8 mg/mL for reducing power, and IC50 = 0.45 mg/mL for hydroxyl radical assay). All the extracts exhibited antimicrobial activity against Gram-positive bacteria, when applied at different concentrations (1–10 mg/mL). Only 50/50 methanol/water and absolute methanol extracts inhibited the growth of Pseudomonas aeruginosa and Klebsiella pneumonia. These interesting biological properties could be attributed to the major identified phenolic compounds, such as caffeic, p-coumaric, ferulic and di-ferulic acids. With this procedure, the GH waste polyphenols could be used as a cheap source of natural compounds, with potential applications in the food and health sectors.