A sealing device for a bearing of the hub of a motor vehicle wheel comprising a stationary race (1) and a rotatable race (2), each defining respective channels (6, 7) for the passage of pressurized air. The sealing device (20) is to be mounted between the rotatable race and the stationary race in order to delimit laterally and hermetically seal an annular space or chamber (14) defined between the bearing races (1, 2) and communicating with the channels (6, 7). The sealing device (20) comprises two sealing units (9) axially facing one another. Each sealing unit (9) comprises an annular reinforcement (10) having an axial cylindrical wall (10a) for mounting to a first bearing race (1) and a radial wall (10b) for reinforcing a flexible gasket (11). The two sealing units (9) are coupled by means of an annular element (21) having a plurality of radial air passages (22). The annular element (21) is located coaxially and forcefully coupled with radial interference with the cylindrical walls (10a) of the two reinforcements (10). The cylindrical walls (10a) of the two reinforcements are axially spaced from one another for allowing pressurized air to flow through the passages (22) of the annular element (21).