Organic matter recycling releases ammonium, and under anoxic conditions, other reduced metabolites that can be used by chemoautotrophs to fix inorganic carbon. Here I present an estimate for the global rate of oceanic carbon fixation by chemoautotrophs (0.77 Pg C y−1). Near-shore and shelf sediments (0.29 Pg C y−1) and nitrifiers in the euphotic zone (0.29 Pg C y−1) and the dark ocean (0.11 Pg C y−1) are the most important contributors. This input of new organic carbon to the ocean is similar to that supplied by world-rivers and eventually buried in oceanic sediments. Chemoautotrophy driven by organic carbon recycling is globally more important than that fuelled by water-rock interactions and hydrothermal vent systems.