In this study, we establish comprehensive design guidelines to maximize single-mode transmission by efficient coupling between a III-nitride quantum-dot-in-nanowire light emitter and a photonic waveguide in the ultraviolet-visible (UV-Vis) spectral range. Considering feasible epitaxial growth, deposition, and fabrication techniques, this study performs detailed electromagnetic simulations to identify the design limits of viable material systems suitable for monolithic integration of vertical III-nitride nanowires on standard ridge waveguides. We show that unlike systems operating in the near-infrared wavelengths, light coupling and transmission in the UV-Vis range are significantly constrained by substrate leakage and backreflection. Such constraints arise from refractive index contrast of the associated waveguide and substrate materials suitable for epitaxial growth and device fabrication. For optimized dimensions of the nanowire and waveguide structures, the maximum unimodal transmission for practical monolithic systems is ∼14% within the wavelength range of 300–500 nm. The theoretical transmission limit of the monolithic system is shown to be 35% with a substrate of unity refractive index. It has been shown that the best strategy of maximizing coupling between the emission mode of the vertical nanowire and the propagation mode of the planar ridge waveguide is to increase the refractive index contrast between the waveguide and substrate material. Based on these key findings, we propose heterogeneously integrated hybrid structures, which significantly exceeds the unimodal transmission limits of standard monolithic systems attainable with III-nitride material systems in the UV-Vis wavelengths.