Bone tissue supports the body, enables movement, protects organs, produces blood cells and stores minerals. In regenerative medicine, bone’s natural healing ability drives the need for engineered solutions to treat fractures, defects, and support implants. This study explores the development of poly(ethylene terephthalate glycol) (PETG) and PETG/bacterial cellulose (BC) composite scaffolds with varying BC contents (10, 15, and 20 wt%) for bone tissue engineering. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed porous structures with increasing surface roughness as BC content rose. Water contact angle analysis showed enhanced hydrophilicity in PETG/BC composites, particularly at higher BC levels. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) confirmed successful BC integration and interactions with PETG, along with increased crystallinity. Mechanical testing indicated that compressive strength improved with higher BC content, with 20 wt% BC achieving optimal performance. Biological tests using human adipose-derived stem cells (hADSc) showed enhanced proliferation, differentiation, and mineralization on PETG/BC scaffolds. Among all, the 20 wt% BC scaffold demonstrated the most favorable physical, mechanical, and biological properties. Overall, PETG/BC scaffolds, especially those with 20 wt% BC, show strong potential for future bone tissue engineering applications.