In this Letter, we report on the fabrication and characterization of a monolithic III–V semiconductor photonic chip, designed to perform nonlinear parametric optical processes for frequency conversion and non-classical state generation. This chip co-integrates an AlGaAs microdisk that is evanescently coupled to two distinct suspended waveguides designed for light injection and collection around 1600 nm and 800 nm, respectively. Quasi-phase matching provided by the resonator geometry and material symmetry, resonant field enhancement, and confinement ensure efficient nonlinear interactions. We demonstrate second-harmonic generation efficiency of 5%W^−1 and a biphoton generation rate of 1.2 kHz/µW through spontaneous down-conversion.