Different molecular weights of polyethylene glycol (PEG, MW 200, 400, 600, 2000, and 4600) were grafted onto silicon tetrachloride (SiCl4) plasma functionalized polyethylene terephthalate (PET) surfaces. Dramatic increase of the C-O peak in the C1s high-resolution spectra determined by electron spectroscopy for chemical analysis suggests that PEG was successfully grafted. PEG-grafted PET showed significant inhibition of attachment and biofilm formation by Salmonella enterica sv. Typhimurium compared to unmodified PET. The antifouling ability of PEG-grafted PET surfaces was affected by the molecular weight of PEG and PEG2000 was the most effective. Both PEG600- and PEG2000-grafted PET also significantly inhibited biofilm formation by Listeria monocytogenes. Stability tests showed that over 2-month storage under ambient conditions PEG2000-grafted PET demonstrated reduced antifouling ability, but still significantly reduced biofilm formation by S. enterica sv. Typhimurium.