A rotor of a turbomachine, such as a multi-flow turbojet engine fan, has a disc including, on the rim thereof, substantially axial slots with a dovetailed cross-section, and blades mounted individually in the slots, an axial wedge positioned between the root of the blades and the bottom of the slots, and a transverse lock providing upstream axial immobilization of the blades in the slot thereof. The lock is guided in radial notches formed in the flanks of the slots and radially supported against the wedge. The axial wedge is immobilised in the upstream direction, butting up against a transverse annular component secured to the disc.