Inspired by the outstanding properties of cobalt-base superalloys, an effort has been made to develop cobalt-base high entropy alloy for high temperature applications based on valance electron concentration (VEC). The newly developed cobalt-base high entropy alloy exhibited a two-phase microstructure with nano lamellar eutectic morphology. The constituent phases were identified as face centered cubic (FCC) and ordered cubic (B2) structure, which were validated through CAlculation of PHAse Diagram (CALPHAD). The newly developed HEA exhibited remarkable strain hardening behavior at room temperature as well as thermal stability in the temperature range 500–800 °C.