Lignin nanoparticles emerged as a promising alternative for drug delivery systems owing to their biodegradability and bioactive properties. This study investigated the antimicrobial activity of the ethanolic extract of loaded lignin nanoparticles (OB-LNPs) and seed oil-loaded lignin nanoparticles (LS-LNPs) to find a solution for antimicrobial resistance. OB-LNPs and LS-LNPs were tested for their antimicrobial potential against , , , , , , , and . OB-LNPs and LS-LNPs were further tested for their anti-efflux activity against ciprofloxacin-resistant strains and for treating infection in a rat model. We also investigated the antifungal efficacy of OB-LNPs and LS-LNPs for treating infection in a guinea pig model. Both OB-LNPs and LS-LNPs showed strong antimicrobial potential against . Typhimurium and infections. LS-LNPs showed antibacterial activity against species with a MIC range of 0.5-4 µg/mL and antifungal activity against with a MIC range of 0.125-1 µg/mL. OB-LNPs showed antibacterial activity against species with a MIC range of 0.5-2 µg/mL and antifungal activity against with a MIC range of 0.25-2 µg/mL. OB-LNPs and LS-LNPs downregulated the expression of and efflux pump genes (fold change values ranged from 0.2989 to 0.5434; 0.4601 to 0.4730 for and 0.3842-0.6199; 0.5035-0.8351 for ). Oral administration of OB-LNPs and LS-LNPs in combination with ciprofloxacin had a significant effect on all blood parameters, as well as on liver and kidney function parameters. Oxidative stress mediators, total antioxidant capacity, and malondialdehyde were abolished by oral administration of OB-LNPs and LS-LNPs (0.5 mL/rat once daily for 5 days). Interferon-γ and tumor necrosis factor-α were also reduced in comparison with the positive control group and the ciprofloxacin-treated group. Histopathological examination of the liver and intestine of OB-LNPs and LS-LNPs-treated rats revealed an elevation in clearance. Treatment of -infected guinea pigs with OB-LNPs and LS-LNPs topically in combination with itraconazole resulted in a reduction in lesion scores, microscopy, and culture results. In conclusion, OB-LNPs and LS-LNPs possess immunomodulatory and antioxidant potential and can be used as naturally derived nanoparticles for drug delivery and treatment of Salmonellosis and dermatophytosis infections.