In this study, a novel polysiloxane with antibacterial and hydrophobic properties was synthesized by introducing N-halamine compound precursor and alkoxy groups. The synthesized polysiloxane was characterized by Fourier transform infrared (FT-IR) spectrometer and 1H nuclear magnetic resonance. The pre-prepared SiO2 sol and synthesized polysiloxane were coated onto the cotton fabrics, and the coated cotton fabrics were characterized by scanning electron microscopy, FT-IR, and X-ray photoelectron spectroscopy. After chlorination, the coated cotton presented hydrophobicity with a contact angle of 130°. The antibacterial test demonstrated that 100% of S. aureus and 99.64% of E. coli O157:H7 could be inactivated with a contact time of 30 min. The coated cotton fabric also showed desired mechanical property and air permeability. In addition, the coated cotton fabric showed excellent stability by measuring the contact angles during washing and UV light stability tests. Although the chlorine content decreased substantially after 50 washing and 24 h UV irradiation, 76.5% and 50.9% of the original chlorine content could be recovered after rechlorination, respectively.