The integration of functional nanomaterials and heterostructures with photonic architectures has laid the foundation for important photonic and optoelectronic applications. The advent of epitaxy and layer lift-off techniques has enabled a wide spectrum of two-dimensional materials and three-dimensional single-crystalline freestanding thin films with diverse optical functionalities, featuring van der Waals (vdW) interfaces suitable for photonic vdW integration. Physical assembly leveraging vdW interactions eliminates the constraints of epitaxial lattice-matching, introducing unprecedented freedom to combine dissimilar materials with appealing optoelectronic properties but radically distinct crystal structures. Various prefabricated vdW building blocks can be combined in novel hetero-integrated photonic architectures and hybrid vdW heterostructures to prototype new devices and explore exotic nanophotonic phenomena at mixed-dimensional vdW interfaces. The ultrathin nature of these freestanding nanomembranes also enables flexible and lightweight photonic devices for low-cost wearable and multifunctional health-care applications. In this Review, we survey the recent progress in photonic nanomembranes with vdW interfaces, discussing a broad range of delaminated freestanding nanomembranes from film preparation to device implementation. We also analyse the remaining challenges and highlight emerging opportunities for advanced vdW hetero-integration.