Mitochondria are «bacteria within» that are crucially involved in multiple host innate immune responses to infection (bacteria and viruses) and sterile cell stress. Mitochondrial function seems to control innate immunity at various stages as diverse as the transcriptional regulation of inflammatory cytokines and chemokines and their maturation by inflammasomes. Mitochondria orchestrate innate immune responses at different levels by promoting a cellular metabolic reprogramming and the cytosolic immune signaling cascades. Mitochondria host a myriad of molecular components involved in innate immune machineries. Mitochondria integrate innate immune sensing of pathogens and cell stress and propagate signals through the release of its components to alert cytosolic sentinels.