The multiple electronic phase transition achieved in the metastable perovskite (ReNiO₃, 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 ReNiO₃. Herein, we synthesize the atomic-level flat ReNiO₃ film material with thermodynamic metastability using laser molecular beam epitaxy (LMBE) that exhibits excellent thermally-driven electronic phase transitions. Notably, the interfacial heterogeneous nucleation of ReNiO₃ film can be triggered by the template effect of (001)-oriented LaAlO₃ substrates, owing to the similar lattice constants between LaAlO₃ substrate and ReNiO₃ film. In addition, we elucidate the key role of in situ annealing under oxygen-enriched atmosphere in stabilizing the distorted perovskite structure related to ReNiO₃. Apart from the depositing process related to LMBE, the ReNiO₃ with heavy rare-earth composition exhibits a more distorted NiO₆ octahedron and a higher Gibbs free energy that is rather difficult to synthesize by using physical vacuum deposition. As a representative case, the in situ annealing-assisted LMBE process cannot be utilized to deposit the SmNiO₃ film, in which the impurity peaks related to Re₂O₃ and 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 ReNiO₃ is found to be +3, and the t_2\mathrmg^6e_\mathrmg^1 configuration is observed. Considering the highly tunable electronic orbital configuration of ReNiO₃ related to the NiO₆ octahedron, co-occupying the A-site of perovskite structure with Nd and Sm elements regulates the transition temperature (T_MIT) for ReNiO₃ within a broad temperature range. Furthermore, we demonstrate the anisotropy in the electronic phase transitions for Nd_1–xSm_xNiO₃, in which case the T_MIT achieved in the Nd_1–xSm_xNiO₃/LaAlO₃ (111) heterostructure exceeds the one deposited on the (001)-oriented LaAlO₃ substrate. The presently observed anisotropy in the electrical transportation for Nd_1–xSm_xNiO₃ film material is related to the anisotropic in-plane NiO₆ octahedron configuration triggered by differently oriented LaAlO₃ substrates. The present work is expected to introduce a new degree of freedom to regulate the electronic phase transition, explore new electronic phase in ReNiO₃ material system, and pave the way for growing atomic-level flat ReNiO₃ film materials with expected electronic phase transitions.