Face-centered-cubic high-entropy alloys have attracted extensive attention due to their comprehensive mechanical and other properties. However, these alloys suffer from low yield strength, making it imperative to develop alloys with high yield and tensile strengths. This study systematically investigates the microstructural characteristics and tensile mechanical properties of the Fe₅₀Mn₂₉-Co₁₀Cr₁₀Cu₁ high-entropy alloy processed by rolling at three temperatures (-196, 25, and 300 °C) followed by annealing. The aim is to elucidate the deformation mechanisms associated with different processing routes and their influences on strength and ductility. During uniaxial tensile deformation, deformation twins produced by liquid-nitrogen and room-temperature rolling along with lath-like reversed austenite impede dislocation slip, thereby improving the yield strength of the alloy. In contrast, the alloy processed by warm rolling and annealing shows few deformation twins, with dislocation slip and stacking faults dominating as the deformation mechanisms. The alloy processed by liquid-nitrogen rolling followed by 500 ^oC annealing exhibits high yield strength but poor plasticity. Conversely, alloys rolled at room temperature and 300 ^oC followed by 500 ^oC annealing demonstrate higher yield strengths and certain degree of work hardening capability, showing corresponding yield strengths of 752 and 604 MPa, tensile strengths of 917 and 784 MPa, and uniform elongations of 11.2% and 26.2%. The differing microstructures resulting from processing at varied temperatures and subsequent annealing lead to significant differences in mechanical behavior under tensile testing.