We report, to the best of our knowledge, the first demonstration of octave-spanning supercontinuum generation (SCG) on a silicon chip, spanning from the telecommunications c-band near 1.5 μm to the mid-infrared region beyond 3.6 μm. The SCG presented here is characterized by soliton fission and dispersive radiation across two zero group-velocity dispersion wavelengths. In addition, we numerically investigate the role of multiphoton absorption and free carriers, confirming that these nonlinear loss mechanisms are not detrimental to SCG in this regime.