The influence of multidirectional isothermal forging on the grain structure and secondary phase particles of solidification origin and dispersoids in Al–4.9Mg–0.9Ni–0.9Fe–0.2Zr–0.1Sc alloy has been studied. The finite element simulation was used to analyze a strain distribution in the sample during forging in a die. A proposed method considered the influence of friction and the changes in a strain rate to recalculate true stress-strain curves for multidirectional forged alloy. An increase in a number of forging cycles at a temperature of 350°C ensured a twice decrease in a mean size of the particles of solidification origin, provided a mean grain size of 1.3 ± 0.2 μm, and insignificantly changed the size of dispersoids. The isothermal multidirectional forging increased the yield strength of the alloy by 60%, tensile strength by 20%.