A sealing device for sealing off external contaminants from a bearing unit between a stationary radially outer ring and a rotatable radially inner ring, the sealing device including a first, metallic and rotatable annular screen having a first mounting area for assembly with interference on the radially inner ring, a second, metallic and stationary annular screen having a second mounting area for assembly with interference on the radially outer ring, an annular sealing element made of elastomeric material, integrally supported by the second annular screen, and equipped with at least one contacting annular sealing lip projecting axially and radially from the second screen towards the first screen, and a non-contacting annular lip extending axially and facing a first flange portion of the first annular screen.