This study aimed to determine the bioactivities and osseointegration activities of Ti-6Al-4V after surface functionalization with a combination of phosphate and calcium. Several Ti-6Al-4V containing different amounts of phosphate and/or calcium on their surface were prepared. Phosphate was introduced by allowing samples to react with H3PO4, and the resulting phosphate-modified samples were further allowed to react with CaCl2 to obtain phosphate- and calcium-co-immobilized samples. Cell studies revealed that the co-immobilization of phosphate and calcium significantly promoted MC3T3-E1 preosteoblast proliferation and osteogenic differentiation, compared to that in unmodified, phosphate-modified, or calcium-modified Ti-6Al-4V. Furthermore, after implants were inserted into the bone marrow cavity of a rat femur, the osseointegration activity and bond strength between implants and the bone were increased in a phosphate- and calcium-functionalized sample, compared to those in a bare sample.