Inconel 718 alloy, with outstanding high-temperature resistance and mechanical properties, has been widely used in aviation fields. However, large and complex structural components are difficult to produce by traditional processes, which may lead to segregation, micropores, and Laves phases. Net-shape hot isostatic pressing (HIP) is a powder metallurgy processing technology that produces near-shape or net-shape components with the desired microstructures, properties, and cost effectiveness. In this study, Inconel 718 pre-alloyed powder was prepared using the electrode induction melting gas atomization technique, and then the pre-alloyed powder was characterized. Powder compacts were prepared by the HIP of the pre-alloyed powder, and their mechanical properties were tested. Although clean, high-quality powder can be obtained from Inconel 718 alloy due to its lower chemical reactivity compared to titanium alloys, carbide-forming elements diffuse to the powder surface during HIP. These form a hard film with the original oxide particles as nuclei, consisting of Ni3Nb and carbides of Ti and Nb. These films become prior particle boundaries (PPBs) in the obtained powder metallurgy Inconel 718 alloy, resulting in lower ductility, toughness, and stress rupture life than those of the wrought version of the alloy. Suppressing the formation of the PPBs during HIP or eliminating them via subsequent processing significantly improves the comprehensive mechanical properties of the material.