Two-dimensional (2D) Ruddlesden–Popper (RP) halide perovskite has attracted significant attention as a promising candidate for high-efficiency light sources. RP perovskites, when synthesized into well-defined nanowires (NWs), have the potential to serve as nanoscale coherent light sources by incorporating optical cavity effects with their light emission behaviors. However, RP perovskites tend to grow in macroscopic thin sheets as opposed to relevant NW structures due to the layered nature of the crystal lattice, which necessitates a new way of controlling nanoscale morphologies. Here, we achieve NWs of RP BA2PbBr4 (BA = butylammonium), for the first time, using chemical vapor deposition (CVD) by systematically navigating a wide range of growth conditions and constructing growth regimes of distinct morphologies. Of the two particular regimes that produce well-formed nanostructures, we find that RP BA2PbBr4 grows into energetically favored thin nanoplatelets (NPLs) at high temperatures, whereas intermediate temperatures allow it to first grow into three-dimensional (3D) pyramidal nuclei and then get elongated into NWs upon continued growth. We propose temperature-dependent diffusion of surface species as a deciding factor of our morphological control. We present crystallographic and elemental analyses to confirm that our NWs have the appropriate lattice structures and chemical stoichiometry of BA2PbBr4. Static and time-resolved optical measurements show quantized absorption and emission features at 400 and 406 nm, respectively, with a radiative decay time of 1.7 ns that is much quicker than the 8.7 ns decay time of a prototypical 3D CsPbBr3 perovskite. The RP NWs exhibit a strong exciton binding energy of 279 meV, which can be understood by the reduced dimensionality of BA2PbBr4. The strong absorption and radiative emission characteristics suggest that the RP BA2PbBr4 NWs are good candidates as bright, ultrasmall light sources for nanophotonic and optical communication applications.