The field of quantum communication and sensing using solid-state qubits faces some critical challenges in qubit creation, control, and readout. To address these challenges, this thesis presents advancements in the laser-driven creation and manipulation of quantum defects in diamond nanostructures. Leveraging the interaction of a pulsed laser with diamond nanophotonic resonators, we generate defects in photonic cavities with enhanced efficiency and scalability. Additionally, we introduce a novel, all-optical approach to tailor the optical properties of quantum defects in diamonds. We also explore the effect of cavity interactions of excitons and trions in 2D materials. Chapter 1 introduces the foundational concepts of color centers in diamond, focusing on nitrogen-vacancy (NV-) centers and Group IV color centers and their integration with nanophotonic cavities. We review established methods for creating these defects and provide an overview of the emerging technique of ultrafast laser writing in diamond. Chapter 2 outlines our experimental setups, especially our custom-built confocal microscope, its several functions throughout our experiments and integration with a pulsed laser-writing setup. Chapter 3 details the fabrication and characterization of integrated nanophotonic devices on our novel thin-film diamond platforms both by direct etching as well as hybrid integration with titanium dioxide (TiO2) devices. We present the processes for creating structures like ring resonators, nanopillars, and bullseye antennas, highlighting the challenges and solutions in achieving high-quality devices compatible with color center integration. Chapter 4 demonstrates cavity-enhanced laser writing as a novel method for creating quantum defects in diamond membranes, highlighting reduced (picojoule) pulse energies compared to laser writing in bulk diamond, thereby relaxing system and substrate requirements. Chapter 5 presents an avenue for optical tuning of germanium-vacancy (GeV-) color centers in a suspended diamond membrane, using pulsed laser irradiation to achieve permanent shifts of the zero-phonon line (ZPL), without the need of complex device integration. Chapter 6 explores the cavity-engineering of exciton and trion lifetimes and emission linewidths in monolayer molybdenum diselenide (MoSe2). Chapter 7 and 8 summarize the key findings and outlines future research directions of cavity-enhanced laser-writing. The work presented in this dissertation significantly contributes to the advancement of quantum technologies by introducing and characterizing novel methods for creating and manipulating quantum defects in diamond using laser engineering. These findings pave the way for the development of more efficient, scalable, and integrated quantum devices.