with different substances; therefore, the resulting change in polarization state can reveal the chemical configuration, [6] structural conformation, [7] and optoelectronic properties of a substance. [8] This chiroptical phenomenon and interpretation of chiral characteristics constitute the basis of chiral photonics. In particular, circularly polarized photoluminescence (CPPL) (i.e., differential emission of left-handed circularly polarized (LCP) and righthanded circularly polarized (RCP) lights) is absolutely necessary for scrutinizing the ground state of materials, [9] whereas circular dichroism (CD) spectroscopy (i.e., differential absorption of LCP and RCP lights) can provide useful information regarding the structure of the excited state of materials. [7] These complementary phenomena enable the development of advanced smart photonic technologies.A material is chiral if it cannot be superimposed on its mirror image. This phenomenon is commonly observed in natural organic compounds, such as small amino acids, saccharide, starch, and DNA. Owing to their noncentrosymmetric structure (e.g., no inversion symmetry, mirror plane, and glide plane), chiral materials exhibit nonlinear optical responses to CPL in CD and CPPL spectra. Although organic chiral materials are ubiquitous and exhibit strong chiroptical activity in the near-UV region, [10] the structural softness of organic chiral molecules makes them difficult to stack, resulting in poor charge transfer capability in practical polarization-based optoelectronic devices. Additionally, in chiral photonics research, focus should be on stable and broad wavelength tunability over the visible light region to realize optoelectronic devices based on the polarization phenomenon. In this regard, OIHPs have emerged as promising candidates for nonlinear optic devices because of their facile color tunability through halide composition engineering, [11] quantum size effects, [12] small effective mass, [13] long spin lifetime exceeding 1 ns, diffusion lengths ≈85 nm, and high electron/hole mobility. [14] A recent study demonstrated that OIHPs exhibit strong spin-orbit coupling of the electronic states, [15] spin-dependent optical selection rules, and large Rashba splitting, [16] suggesting that the OIHPs might exhibit exceptional spin polarization properties. [17] Despite the exceptional spin polarization properties, OIHP materials cannot be utilized in chiral photonics owing to their centrosymmetric crystal structure. However, the flexible crystal Organic-inorganic hybrid halide perovskites (OIHPs) are commonly used as prototypical materials for various applications, including photovoltaics, photodetectors, and light-emitting devices. Since the chiroptical properties of OIHPs are deciphered in 2017, chiral OIHPs have been rediscovered as new hybrid systems comprising chiral organic molecules and achiral inorganic octahedral layers. Owing to their exceptional optoelectrical properties and structural flexibility, chiral OIHPs have received a considerable amount of attention...