Biopolymer/bioceramic composites were prepared by blending acetylated chitosan (ACS) with carbonated nano-size hydroxyapatite (CHAP) for use as a guided tissue regeneration barrier. The carbonate group of CHAP was a partial substitution of the hydroxyl group and/or phosphate group of hydroxyapatite by sintering with carbon dioxide. Chitosan/CHAP composites were acetylated with acetic anhydride to form the ACS/CHAP composites. The compositions and properties of the composites were confirmed by Fourier transform infrared spectroscopy, inductively coupled plasma mass spectrometry, zeta potential analysis, X-ray diffraction analysis, universal testing machine analysis, scanning electron microscopy, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, etc. The surface energies of the composites were increased by carbonation and acetylation. The acetylation of chitosan increased the lysozyme degradation of the composite. The carbonation of hydroxyapatite significantly improved the viability of osteoblast-like cell on the composite. The high viability and intact phenotype of cell occurred on composite with ACS/CHAP ratio of 50/50, which had sufficient elastic modulus for a guided bone regeneration barrier.