In less than a decade, the mid-infrared (mid-IR) spectral range (2.5-12 μm) has become a key application for innovative silicon photonic devices because of the growing potential in spectroscopy, materials processing, chemical and biomolecular sensing, security and industry applications. We review the latest developments of emitters (GeSn lasers or heterogeneous quantum cascade laser on Si), passive devices (Silicon on Insulator, suspended Si or Ge waveguides, and SiGe/Si waveguides, Ge/SiGe waveguides), highly efficient nonlinear devices as well as integrated detectors for mid-IR applications. Perspectives for potential applications will also be discussed.