The mechanical properties of virgin/recycled high-density polyethylene (HDPE) blends over the complete concentration range was thoroughly investigated in this work. In particular, a focus was made on the long-term properties via mechanical fatigue. Two different mixing methods, namely powder mixing (dry blending) and extrusion mixing (melt blending), were used to determine the effect of processing conditions on the tensile and fatigue behavior of the blends after compression molding. It was found that both tensile (modulus, ultimate strength) and fatigue performances were improved with increasing vHDPE content. Based on the obtained data, a correlation between the blends composition and mechanical properties is reported. Moreover, it was observed that increasing the vHDPE content led to slower crack propagation rate, probably due to less defects (contamination) in the blends. Finally, a negligible difference in mechanical properties (fatigue resistance) between both mixing approaches was observed, but samples produced via powder mixing showed less viscous dissipation (heat generation) as the vHDPE content increased, leading to lower surface temperature rise which can be an advantage for specific applications.