A process for manufacturing a multi-layered sole directly on the upper, of the type that employs the technique known as "direct injection on the upper", by which soles are made of a plastic material and consist of a plurality of layers with different colour, density, softness and physical-mechanical properties. Said layers form at least an external sole, called "outsole", an internal sole, called "insole" that adheres and extends only partially or totally on the surface of the upper, and an intermediate sole, called "midsole", that is intended to hold the other two above-said soles. Said process provides for the use of a single mould which is brought, when suitably equipped (100.1,100.2,100.3), in a well-defined sequence, in front of at least three distinct injectors (I1, I2, I3) in order to obtain, also in sequence, by at least a first moulding operation (P1) the lower portion of the sole, i.e. the "outsole", by at least a second moulding operation (P2) the upper part of the sole, i.e. the "insole" and by at least a third moulding operation (P3) the "midsole".