This study presents a single photon emitter deterministically coupled to a second-order topological corner state in a photonic crystal cavity. The quantum dot (QD) is integrated into a photonic crystal cavity with a topologically nontrivial structure, enabling strong light-matter interactions. The cavity exhibits a high Purcell factor of 3.7, achieved through precise alignment of the QD with the cavity mode. The emitted photons show low second-order autocorrelation $ g^{(2)}(0) \approx 0.024 \pm 0.103 $, indicating anti-bunching behavior. The cavity also enables efficient polarization modulation, with the emitted photons being linearly polarized. The design allows for the customization of light-matter interactions in topologically nontrivial environments, offering promising applications in quantum photonics. The topological corner state provides a smaller mode volume and higher Purcell factor compared to other lattice structures, making it an excellent platform for quantum emitters. The study demonstrates the deterministic coupling of a single QD to a topological cavity, achieving significant enhancements in spontaneous emission and photon emission rates. The results highlight the potential of topological photonics in developing robust quantum light sources with high purity and indistinguishability. The findings open new possibilities for topological-cavity-based single-photon sources, which could advance quantum optics interfaces and explore light-matter interactions at the single-photon level. The study also addresses challenges in coupling single QDs to highly confined topological cavities, offering a solution through a novel cavity design and wide-field PL imaging technique. The results demonstrate the feasibility of deterministic coupling and the potential for further improvements in cavity quality and Purcell enhancement through advanced fabrication techniques.This study presents a single photon emitter deterministically coupled to a second-order topological corner state in a photonic crystal cavity. The quantum dot (QD) is integrated into a photonic crystal cavity with a topologically nontrivial structure, enabling strong light-matter interactions. The cavity exhibits a high Purcell factor of 3.7, achieved through precise alignment of the QD with the cavity mode. The emitted photons show low second-order autocorrelation $ g^{(2)}(0) \approx 0.024 \pm 0.103 $, indicating anti-bunching behavior. The cavity also enables efficient polarization modulation, with the emitted photons being linearly polarized. The design allows for the customization of light-matter interactions in topologically nontrivial environments, offering promising applications in quantum photonics. The topological corner state provides a smaller mode volume and higher Purcell factor compared to other lattice structures, making it an excellent platform for quantum emitters. The study demonstrates the deterministic coupling of a single QD to a topological cavity, achieving significant enhancements in spontaneous emission and photon emission rates. The results highlight the potential of topological photonics in developing robust quantum light sources with high purity and indistinguishability. The findings open new possibilities for topological-cavity-based single-photon sources, which could advance quantum optics interfaces and explore light-matter interactions at the single-photon level. The study also addresses challenges in coupling single QDs to highly confined topological cavities, offering a solution through a novel cavity design and wide-field PL imaging technique. The results demonstrate the feasibility of deterministic coupling and the potential for further improvements in cavity quality and Purcell enhancement through advanced fabrication techniques.