N-type Bi₂Te_2.67Se_0.33 thermoelectric materials with added constituent elements were prepared without the addition of harmful dopants using mechanical alloying (MA) followed by hot pressing (HP). All the prepared samples were identified from the Bi₂Te₃–Bi₂Se₃ solid-solution diffraction peak. They were all single-phase n-type semiconductors. The maximum dimensionless figures of merit, ZT, of Bi₂Te_2.67(Se_0.33)_1+0.06, Bi₂(Te_2.67)_1+0.06Se_0.33, and Bi₂(Te_2.67Se_0.33)_1+0.03 were 0.93 at 440 K, 0.99 at 441 K, and 0.97 at 442 K, respectively. These results indicate that the figure of merit of Bi₂Te_2.67Se_0.33 doped with constituent elements, prepared using the MA–HP process, is nearly same as the highest value, i.e., 1.0, reported in the literature.