Ti-13Mn was fabricated using a metal injection molding method to develop a new low-cost high-strength β-type titanium alloy. The Vickers hardness, ultimate tensile strength (UTS), and elongation of the as-sintered and solutionized Ti-13Mn are 284 Hv and 279 Hv, 840 MPa and 880 MPa, and 0.9% and 1.2%, respectively. Although the elongation of the as-sintered and solutionized Ti-13Mn is lower than that of aged Ti-6A1-4V (Ti64) ELI, its UTS is the same as that of aged Ti64 ELI. Moreover, after Ti-13Mn being subjected to 90% cold rolling, its Vickers hardness and UTS significantly increased to 460 Hv and 1852 MPa, respectively. The UTS of cold-rolled Ti-13Mn can be considered extremely high among those of β-type titanium alloys, including Ti-15V-3Al-3Sn-3Cr. The increase in the dislocation density, the formation of a deformation-induced ω phase, and the decrease in porosity result in the strengthening of the solutionized Ti-13Mn.