Powder metallurgy route has been employed to synthesize nanocrystalline Ti2NiCoSn1−xSb1+x (x = 0.3, 0.5, 0.7, 1) alloys for thermoelectric applications. Atom probe analysis confirmed the homogeneous distribution of elements in the half-Heusler phase at a scale of few nanometers. A combination of nanostructuring, lattice distortion and interfacial scattering brings about a reduction in lower thermal conductivity which brings forth an improvement in ZT. Ti2NiCoSb2 exhibited the highest ZT of 0.26 due to the increments effected by higher power factor and lower thermal conductivity.