A method of continuous hydrothermal carbonization of sludge containing organic matter, involving a stage of hydrothermal reaction carried out in a reactor (4), includes: a step of introduction of sludge in which the sludge is introduced into the reactor (4) by a first inlet (11), a step of endogenous injection of steam in which steam is injected into the reactor (4) by a second inlet (15) distinct from the first inlet (11), a step of extraction in which at least a portion of the sludge contained in the reactor (4) is extracted continuously by a sludge outlet (16), a step of preheating in which the temperature of the sludge is raised prior to its introduction into the reactor (4) up to a temperature of preheating greater than 70° C. Also disclosed is a device making it possible to carry out such a method.