The multiple electronic phase transition achieved in the metastable perovskite (ReNiO ₃, where Re denotes a lanthanide rare-earth element) by using critical temperature, hydrogenation, electrical field and interfacial strain has attracted considerable attention in condensed matter physics and materials science, making it promising applications in the critical temperature thermistor, artificial intelligence, energy conversion and weak electric field sensing. Nevertheless, the above abundant applications are still bottlenecked by the intrinsically thermodynamic metastability related to ReNiO ₃. Herein, we synthesize the atomic-level flat ReNiO ₃film material with thermodynamic metastability using laser molecular beam epitaxy (LMBE) that exhibits excellent thermally-driven electronic phase transitions. Notably, the interfacial heterogeneous nucleation of ReNiO ₃film can be triggered by the template effect of (001)-oriented LaAlO ₃substrates, owing to the similar lattice constants between LaAlO ₃substrate and ReNiO ₃film. In addition, we elucidate the key role of in situannealing under oxygen-enriched atmosphere in stabilizing the distorted perovskite structure related to ReNiO ₃. Apart from the depositing process related to LMBE, the ReNiO ₃with heavy rare-earth composition exhibits a more distorted NiO ₆octahedron and a higher Gibbs free energy that is rather difficult to synthesize by using physical vacuum deposition. As a representative case, the in situannealing-assisted LMBE process cannot be utilized to deposit the SmNiO ₃film, in which the impurity peaks related to Re ₂O ₃and NiO are observed in its XRD spectra. With the assistance of X-ray photoelectron spectraoscopy and near-edge X-ray absorption fine structure, the valence state of nickel for ReNiO ₃is found to be +3, and the $t_{2{\mathrm{g}}}^6e_{\mathrm{g}}^1 $ configuration is observed. Considering the highly tunable electronic orbital configuration of ReNiO ₃related to the NiO ₆octahedron, co-occupying the A-site of perovskite structure with Nd and Sm elements regulates the transition temperature ( T _MIT) for ReNiO ₃within a broad temperature range. Furthermore, we demonstrate the anisotropy in the electronic phase transitions for Nd _1–xSm _xNiO ₃, in which case the T _MITachieved in the Nd _1–xSm _xNiO ₃/LaAlO ₃(111) heterostructure exceeds the one deposited on the (001)-oriented LaAlO ₃substrate. The presently observed anisotropy in the electrical transportation for Nd _1–xSm _xNiO ₃film material is related to the anisotropic in-plane NiO ₆octahedron configuration triggered by differently oriented LaAlO ₃substrates. The present work is expected to introduce a new degree of freedom to regulate the electronic phase transition, explore new electronic phase in ReNiO ₃material system, and pave the way for growing atomic-level flat ReNiO ₃film materials with expected electronic phase transitions.