This article presents a novel approach to engineering asymmetric transmission between left-handed and right-handed circularly polarized light (LCP and RCP) in planar Fabry-Pérot (FP) microcavities. The key innovation is the use of organic thin films exhibiting apparent circular dichroism (ACD), a phenomenon based on 2D chirality. ACD interactions are opposite for counter-propagating light, leading to asymmetric transmission over an order of magnitude larger than that of isolated thin films. The study demonstrates the spatial, spectral, and angular chiroptical responses of this 2D chiral microcavity through circular dichroism spectroscopy, Mueller matrix ellipsometry, and theoretical scattering matrix methods. The 2D chiral microcavity is created by embedding a self-assembled chiral thin film, such as (S,S)-PTPO, between two highly reflective mirrors. The chiral thin film exhibits ACD, which allows for asymmetric transmission of LCP and RCP light. The microcavity enhances the chiroptical response by amplifying the ACD signals over multiple round trips within the cavity, resulting in a significant increase in the circular dichroism (CD) values. The experimental results show that the CD values in the 2D chiral microcavity are significantly higher than those in the thin film on a high reflectivity (HR) substrate, reaching nearly 1000 mdeg for 50 nm films and nearly 2000 mdeg for 100 nm films. The angular dispersion of the microcavity is also studied, showing that the CD value is higher at oblique incidence than at normal incidence, which is attributed to the increased path length through the thin film. The 2D chiral microcavity offers new opportunities for chiral engineering without the need for complex nanofabrication, providing a powerful photonic interface for quantum transduction. The study highlights the potential applications in quantum information science, polaritonics, and chiral lasing.This article presents a novel approach to engineering asymmetric transmission between left-handed and right-handed circularly polarized light (LCP and RCP) in planar Fabry-Pérot (FP) microcavities. The key innovation is the use of organic thin films exhibiting apparent circular dichroism (ACD), a phenomenon based on 2D chirality. ACD interactions are opposite for counter-propagating light, leading to asymmetric transmission over an order of magnitude larger than that of isolated thin films. The study demonstrates the spatial, spectral, and angular chiroptical responses of this 2D chiral microcavity through circular dichroism spectroscopy, Mueller matrix ellipsometry, and theoretical scattering matrix methods. The 2D chiral microcavity is created by embedding a self-assembled chiral thin film, such as (S,S)-PTPO, between two highly reflective mirrors. The chiral thin film exhibits ACD, which allows for asymmetric transmission of LCP and RCP light. The microcavity enhances the chiroptical response by amplifying the ACD signals over multiple round trips within the cavity, resulting in a significant increase in the circular dichroism (CD) values. The experimental results show that the CD values in the 2D chiral microcavity are significantly higher than those in the thin film on a high reflectivity (HR) substrate, reaching nearly 1000 mdeg for 50 nm films and nearly 2000 mdeg for 100 nm films. The angular dispersion of the microcavity is also studied, showing that the CD value is higher at oblique incidence than at normal incidence, which is attributed to the increased path length through the thin film. The 2D chiral microcavity offers new opportunities for chiral engineering without the need for complex nanofabrication, providing a powerful photonic interface for quantum transduction. The study highlights the potential applications in quantum information science, polaritonics, and chiral lasing.