<p>This study investigated the hot deformation behavior of the multicomponent CoCrFeNiNb_0.45 eutectic alloy. An Arrhenius-type constitutive equation was established based on the acquired stress–strain curves, and the effects of temperature and strain rate on the as-deformed microstructure were analyzed. The results show that the peak flow stress of the alloy decreases with a rise in temperature but increases with the rising of strain rate. With the increase in temperature and strain rate, deformation-induced ultrafine grains gradually disappear, and the lamellar features of the eutectic structure become progressively weakened, such that each lamellar colony corresponding to the eutectic FCC and HCP phases comprises multiple fine grains rather than a monolithic grain. Meanwhile, the solidification-inherited crystallographic preferred orientation gradually diminishes. Low-angle grain boundaries (LAGBs) are mainly distributed in the FCC phase, while high-angle grain boundaries (HAGBs) are concentrated in the HCP phase. The fraction of LAGBs decreases with the increase in both temperature and strain rate. Twinning nucleation and growth occur in the FCC phase but are completely absent in the HCP phase. The twin boundaries (TBs) of the FCC phase transform from a dense, short morphology to a sparse, elongated one, and the TB fraction first increases gradually and then stabilizes when temperature and strain rate increase. The dynamic recrystallization (DRX) degree of the alloy rises with a rise in temperature, and an elevation in strain rate beyond the recrystallization threshold can effectively promote the DRX degree. The DRX behavior of the alloy during hot compression is primarily dominated by the softening effect of the FCC phase.</p>