<p>This present work focuses on the synthesis of scrambled SmNiO₃ nanopins by the hydrothermal route, structural and morphological characterizations, and observing their potential electric field emission response with density functional theory (DFT) study. The Rietveld refinement of X-ray diffraction (XRD) and Raman characterization study reveals an orthorhombic phase (space group <i>Pnma</i>, No. 62) of SmNiO₃, along with Raman-active NiO₆ octahedral vibrational modes and Sm-O lattice motion. The high-resolution scanning and tunneling electron microscopy images exhibit monodispersed hierarchically self-assembled pin-like surface morphology with a crystal lattice spacing of 3.16 Å for 110 planes, which offers exceptional field emission response. The chemical states of Sm, Ni, and O were interpreted by X-ray photoelectron (XPS) spectroscopy in +3 oxidation states (4f⁵ configuration), mixed Ni³⁺/Ni²⁺ valence states, and -2 lattice and defect states, respectively. The current density (J) vs. electric field (E) plots demonstrate a maximum field emission current density ~ 30 µA/cm² @ 8.4 V/µm, and very enduring field emission current stability was observed over a long period of time, 3 h 20 min, with bright field emission fringes. Very low turn-on (E_turn-on) and threshold (E_threshold) were discerned ~ 5.1 V/µm @1 µA/cm² and ~ 7.64 V/µm @10 µA/cm² from J-E curves. The local work function (φ) was calculated to be ~5.13 eV by density functional theory (DFT) calculations, and the field enhancement factor (β) was measured to be ~3343. The noteworthy electric field emission response, low turn-on field, and long-term stable field emission enable SmNiO₃ nanopins to be a high-efficiency electron source for field-emitting display (FED), X-ray source, vacuum transistor device, etc.</p>