The invention relates to a method for producing a turbomachine blade from a composite material, having an integrated platform and/or shroud. The method comprises the following steps: the three-dimensional weaving of a flexible fibrous blank as a single part comprising blade vane (220) and root (230) preform portions; the separate production of a blade platform (400) or blade shroud (500) element comprising a stiffened fibrous reinforcement, whereby at least one opening in the shape of the vane profile of the blade to be produced is formed in the platform or shroud element; the mounting of the platform or shroud element, by means of the opening therein, on the flexible fibrous blank, with deformation of the latter, for assembly with the fibrous blank; the forming of the fibrous blank with the assembled platform or shroud element in order to obtain a preform (200) having a shape similar to that of the blade to be produced; the setting of the shape of the preform in a former; and the introduction of a matrix in the preform in order to obtain a blade made from a composite material and having an integrated platform or shroud.