<p>A novel class of materials known as high entropy alloys (HEAs) is distinguished by its distinct composition, which consists of several primary elements alloyed in almost equimolar ratios. High strength, superior corrosion resistance, and enhanced thermal stability are just a few of the remarkable mechanical qualities displayed by these materials. The potential for increased toughness, which is essential for structural applications in challenging conditions is one of the most exciting features of high entropy alloys. Their exceptional mechanical performance has been attributed to a variety of toughening mechanisms that function at different scales, including atomic, microstructural, and macroscopic levels, according to recent studies. This review presents an overview of the multiscale toughening mechanisms of HEAs, with an emphasis on both intrinsic and extrinsic contributions. The high configurational entropy that HEAs have by nature is essential for solid solution strengthening and maintaining intricate dislocation structures at the atomic scale. Furthermore, these alloys slow diffusion and high stacking fault energy, may prevent dislocation motion, increases their resistance to crack initiation and propagation. Complex phases including face-centered cubic (FCC), body-centered cubic (BCC), and amorphous phases produce a complex microstructure at the microstructural scale that provides several channels for energy dissipation during deformation. By reducing brittle fracture behavior, precipitate strengthening processes and fine-scale phase separation result in increased toughness<b>.</b></p>