Functional ions and drug factors play a vital role in stimulating bone tissue regeneration as we understand it. In this work, europium-containing mesoporous bioactive glass nanospheres (Eu/MBGs), composed of 60% SiO₂—(36–x)%CaO—x%Eu₂O₃—4%P₂O₅ (x = 0, 0.5, 1, 2 mol%), were prepared by a facile sol-gel process. The results indicate that Eu ions play an important role to influence the microstructure of MBGs, in which a suitable concentration of Eu (1 mol%) increases their surface area (502 m²/g) as well as their pore volume (0.34 cm³/g). Proper doping of Eu ions in MBGs can observably induce apatite mineralization and improve the doxorubicin (DOX) release behavior. Furthermore, DOX-loaded Eu/MBGs could maintain a long-term inhibitory effect on the viability of osteosarcoma MG 63 cells. This work has demonstrated that it is possible to develop functional Eu/MBGs by combining excellent apatite-mineralization ability, controllable drug (DOX) release and antitumor functions for the therapy of bone tissue regeneration.