Inconel 718, a Ni–Fe-based alloy, is applied in aerospace and gas turbine applications owing to its excellent resistance to high temperatures and extreme environments, leading to an increasing demand for improved workability. Delta processing (DP) influences the microstructural characteristics of Inconel 718 via controlled heat treatment to precipitate the δ phase. This study investigated the effect of DP on the microstructure and high-temperature workability of Inconel 718. Homogenization and DP after homogenization were applied to control the initial microstructure. High-temperature compression tests were conducted at 900–1150 °C with strain rates of 0.01–10 s -1 and true strain of 1.0. An Arrhenius-based constitutive model was derived and processing maps were established to evaluate workability. Electron backscatter diffraction analyzed microstructure evolution and relationships among workability, mechanical properties, and microstructure. Surface cracks were observed in specimens homogenized at 1150 °C due to NbC precipitation along grain boundaries. Generally, the δ phase and NbC exhibit competitive precipitation behavior for Nb consumption, and DP can effectively suppress NbC formation by preferentially precipitating the δ phase, preventing grain boundary weakening and crack initiation. Furthermore, the δ phase provides preferential nucleation sites for dynamic recrystallization, promoting grain refinement during deformation. The DP-treated specimens exhibited improved hot workability with enhanced microstructural stability and crack prevention. This study confirmed that DP can improve the hot workability of Inconel 718 by suppressing NbC precipitation, which promotes crack formation, and promoting dynamic recrystallization through recrystallization nucleation, thereby offering insights into microstructure control with guidelines for process design and optimization. • δ phase precipitation increased peak stress and work hardening during hot deformation. • DPed specimen showed lower activation energy and enhanced DRX sensitivity. • Processing maps showed wider high-efficiency domains and better workability in DPed. • δ phase precipitation prevented NbC-induced cracking and improved hot workability. • DPed specimens showed greater DRX and grain refinement with homogeneous structure.