Biochemicals production from the energy crop, sweet sorghum [Sorghum bicolor (L.) Moench], has attracted wide attention. However, utilization of sweet sorghum for phenolic compounds production has not yet been reported. To improve comprehensive utilization of sweet sorghum, a strategy combining acidic ethanol extraction and ion precipitation was developed to extract highly active phenolic compounds from sweet sorghum fresh stalks, which increased the final total phenolic content to 276.79 mg gallic acid equivalents/g dried extract. The sweet sorghum phenolic compounds extract was rich in gallic, gentisic, trans-ferulic, caffeic, coumaric, chlorogenic, and p-hydroxybenzoic acids, showing strong antioxidant properties. Evaluation of cell membrane integrity and biomacromolecules (protein and nucleic acid) leakage revealed that the sweet sorghum phenolic compounds extract had significant bacteriostatic activity against Staphylococcus aureus CMCC26003 and Escherichia coli CMCC44102, suggesting potential antimicrobial effects. This study provided a novel strategy for comprehensive utilization of sweet sorghum.