Abstract: The mid-infrared (MIR) wavelength coincides with various molecular resonances and spectroscopy. It is a universal way to identify chemical and biological substances. Thus, the MIR supercontinuum generation (SCG) is widely used in biomedicine, spectroscopy, and environmental science. Cadmium telluride (CdTe) has an ultra-broad transparent spectral range, from 0.86 µm to 25 µm, and one of the largest third-order nonlinear coefficients. It makes CdTe become an excellent candidate for long-wavelength MIR on-chip SCG. As an important material of solar cells, there is a well-established thin film growth technology for CdTe. We designed a CdTe integrated waveguide on a low-refractive-index CdS film with a silicon substrate. The simulation results solved by the nonlinear Schrödinger equation manifest that the MIR SCG covering 4.1 µm to 9.7 µm can be generated from a 1 cm CdTe waveguide pumped by a 5.5 µm femtosecond laser. We experimentally fabricated the waveguide via the lithography and wet-etching techniques. The spectral broadening based on self-phase modulation from the large-core CdTe integrated waveguide is demonstrated by a femtosecond laser at the central wavelength of 1030 nm with a pulse width of 250 fs. The numerical simulations match well with the experimental results. These results pave the way for long-wavelength mid-infrared light sources and provide abundant new opportunities for MIR micro photonics.