The article reviews recent advancements in using flat optics to generate quantum light sources, focusing on the generation of entangled photon pairs through spontaneous parametric down-conversion (SPDC) in nonlinear metasurfaces and single-photon emission from quantum emitters such as quantum dots and color centers in 3D and 2D materials. The review covers theoretical principles, fabrication techniques, and properties of these sources, emphasizing the enhanced generation and engineering of quantum light sources using optical resonances supported by nanostructures. The authors discuss the diverse applications of these sources, including quantum sensing, communication, and imaging, and highlight current challenges and future perspectives in the field. Key functionalities of metasurfaces, such as enhanced light-matter interactions, wavefront control, polarization control, and spectral control, are also discussed, along with their applications in quantum light source development. The review concludes by addressing the challenges and potential directions for future advancements in quantum light sources.The article reviews recent advancements in using flat optics to generate quantum light sources, focusing on the generation of entangled photon pairs through spontaneous parametric down-conversion (SPDC) in nonlinear metasurfaces and single-photon emission from quantum emitters such as quantum dots and color centers in 3D and 2D materials. The review covers theoretical principles, fabrication techniques, and properties of these sources, emphasizing the enhanced generation and engineering of quantum light sources using optical resonances supported by nanostructures. The authors discuss the diverse applications of these sources, including quantum sensing, communication, and imaging, and highlight current challenges and future perspectives in the field. Key functionalities of metasurfaces, such as enhanced light-matter interactions, wavefront control, polarization control, and spectral control, are also discussed, along with their applications in quantum light source development. The review concludes by addressing the challenges and potential directions for future advancements in quantum light sources.