Since sodium is substantially less expensive and more abundant than lithium, sodium-ion batteries (SIBs) are considered a desirable alternative to lithium-ion batteries. As for anode side, conversion and alloy electrode materials are attractive because of their high capacity when reacting with sodium ions, even at high rates. However, the deposition of metallic Na on the anode surface is an issue, which, in turn, jeopardizes the safety of the battery. Recently, several metal oxides have been introduced as anodes for SIBs, such as anatase TiO₂, TiO₂(B), Li₄Ti₅O₁₂. The main disadvantage of using transition metal oxides for Na⁺-ion batteries is the sluggish kinetics of insertion of Na⁺ ions into the structure. Here, we introduce nanosized anatase TiO₂ that is partially doped with fluorine (TiO_2-dF_d) to form electro-conducting trivalent Ti³⁺ as an ultrafast Na⁺ insertion material for use as an anode for sodium-ion batteries. In addition, the F-doped TiO_2-dF_d is modified by electro-conducting carbon nanotubes (CNTs) to further enhance the electric conductivity. The first discharge capacity of the F-doped TiO₂ embedded in CNTs is approximately 250 mAh (g-oxide)^-1, and is retained at 97% after 100 cycles. As expected, a high-rate performance was achieved even at the 100 C discharging rate (25 A g^-1) where the composite material demonstrated a capacity of 118 mAh g^-1 under the 0.1C-rate charge condition