This work presents the design, fabrication, and characterization of a monolithic and complementary-metal–oxide–semiconductor (CMOS)-based integrated optical system, including the light emitter working in the visible range, waveguide, and photodetector. The presented system aims to be applied for the development of optochemical sensors. The work presents the proposed concept and the integration strategy, as well as the fabrication process. The individual elements of the system are theoretically evaluated to assure compatibility among them. Then, the fabrication and studies to the complete system are presented. The response of the light sensor is shown to be caused by optical stimulation of light originated in the integrated light source and transmitted through a dielectric waveguide, thus validating the integration procedure.