The dissertation focuses on the engineering of light-matter interaction using plasmonic nanoparticles and metamaterials to achieve enhanced luminescence and based on which to improve the performance of biosensing and light-emitting technologies. We designed and fabricated a spectrum of nanostructures to exhibit particular dispersion relations capable of controlling the spontaneous emission properties of quantum emitters, such as quantum dots and organic fluorophores. To realize the concept, we developed a metal-assisted focused-ion beam nanopatterning technology to fabricate the plasmonic nanostructures with high-definition. We demonstrated a silver open-ring nanoarrays (ORA) for broadband enhancement of QD emission that was further exploited to demonstrate ultrasensitive DNA sensing. The ORA design offers multiple resonance peaks to support both Purcell effect and excitation enhancement, resulting in a maximal enhancement in QD emission of greater than 100 times and significant improvement in the limit-of-detection of DNA sensing by four orders of magnitude. Another plasmonic nanostructure, aluminum dimple array, was developed to take advantage of the inherent UV plasmonic property of aluminum for broadband enhancement of QD emission. The device may find major applications in optoelectronic devices. While the small-area plasmonic devices are suitable to enhance the fluorescence-based sensors on a chip, there exists a need for large-area enhancement for several applications. For this purpose, we developed multilayered hyperbolic metamaterials accompanied with an efficient light-extraction approach to achieve enhanced quantum dot emission over a large area. Lastly, we expanded the enhancement strategy using plasmonic nanoparticles to improve carbon dot-based microLEDs. The embedded plasmonic nanoparticles were utilized to enhance carbon dot emission while minimizing the UV excitation leak–age. This research provides a set of design rules for enhanced spontaneous emission and the demonstrated applications are expected to pave the way to advanced photonic, biosensing, and optoelectronic devices.