We report the structural and thermoelectric properties of Ni and Te co-doped $Cu{_2}Se$. Densified Ni and Te doped $Cu{_2}Se$ pellets were achieved by melting, quenching and spark plasma sintering route. Temperature-dependent XRD revealed that Ni and Te doping stabilized the cubic and monoclinic phases of $Cu{_2}Se$, respectively. Monoclinic to cubic phase transition temperature of $Cu{_2}Se$ has increased from 400 K to 410 K and 420 K with the doping of 1 at.% Ni and Te, respectively. A negative change of liner thermal expansion around the crystal structure transformation temperature was observed from the dilatometry studies. Thermoelectric properties were recorded in the temperature range of 300 K to 700 K. Ni and Te has played discrete role in improving the thermoelectric properties of $Cu{_2}Se$. Doping 1 at.% Ni onto Cu site has improved the electrical conductivity from 0.22 to 0.31 $MS/m$ at 373 K, whereas doping 1 at.% Te onto Se site enhance the Seebeck coefficient from 50 to 75 $\mu$V/$\kappa$ at 373K. The power factor of $Cu{_2}Se$  has been significantly improved to 850 $\mu$W/m.$K^2$ with the co-doping of  1 at.% Ni and Te at 373 K. Thermal conductivity of undoped $Cu{_2}Se$ was reduced drastically from(7 $W/m.K$) to (0.3 $W/m.K$) with the 1 at.% Ni and Te co-doping at 373 K. Improved power factor and reduced thermal conductivity together contribute to twenty fold increment in the figure of merit of 1 at.% of Ni and Te co-doped $Cu{_2}Se$ (ZT = 0.4), compared to the undoped $Cu{_2}Se$ (ZT = 0.025) at 373 K. Our results established that the co-doping strategy is a promising route to improve the figure of merit of inorganic materials.