The fabrication of Ti-Mg composite biomaterials was investigated using spark plasma sintering (SPS) with varying Mg contents and sintering pressures. The effects of powder mixing, Mg addition, and sintering pressure on the microstructure and mechanical properties of the composite materials were systematically analyzed. Uniform dispersion of Mg within the Ti matrix was achieved, confirming the efficacy of ethanol-assisted ball milling for consistent mixing. The Young's modulus of the composite materials exhibited a linear decrease with increasing Mg content, with Ti-30vol%Mg and Ti-50vol%Mg demonstrating reduced modulus values compared to pure Ti. Based on density measurements, compression tests, and Young's modulus results, it was determined that the sinterability of Ti-30vol%Mg saturates at a sintering pressure of approximately 50 MPa. Moreover, our immersion tests in physiological saline underscore the profound significance of our findings. Ti-30vol%Mg maintained compressive strength above that of cortical bone for 6-to-10 days, with mechanical integrity improving under higher sintering pressures. These findings mark a significant leap towards the development of Ti-Mg composite biomaterials with tailored mechanical properties, thereby enhancing biocompatibility and osseointegration for a wide range of biomedical applications.