Abstract3D organic‐inorganic metal halide perovskites are excellent materials for optoelectronic applications due to their exceptional properties, solution processability, and cost‐effectiveness. However, the lack of environmental stability highly restricts them from practical applications. Herein, a stable centimeter‐long 2D hybrid perovskite (N‐MPDA)[PbBr₄] single crystal using divalent N1‐methylpropane‐1,3‐diammonium (N‐MPDA) cation as an organic spacer, is reported. The as‐grown single crystal exhibits stable optoelectronic performance, low threshold random lasing, and multi‐photon luminescence/multi‐harmonic generation. A photoconductive device fabricated using (N‐MPDA)[PbBr₄] single crystal exhibits an excellent photoresponsivity (≈124 AW⁻¹ at 405 nm) that is ≈4 orders of magnitudes higher than that of monovalent organic spacer‐assisted 2D perovskites, such as (BA)₂PbBr₄ and (PEA)₂PbBr₄, and large specific detectivity (≈10¹² Jones). As an optical gain media, the (N‐MPDA)[PbBr₄] single crystal exhibits a low threshold random lasing (≈6.5 µJ cm⁻²) with angular dependent narrow linewidth (≈0.1 nm) and high‐quality factor (Q ≈ 2673). Based on these results, the outstanding optoelectronic merits of (N‐MPDA)[PbBr₄] single crystal will offer a high‐performance device and act as a dynamic material to construct stable future electronics and optoelectronic‐based applications.