A slewing bearing including a first ring, a second ring, the first and second rings being in relative rotation around a rotation axis, at least one row of rolling elements arranged between the rings, and at least two seals having each an annular heel mounted on a cylindrical frontal surface of first ring, and an oblique sealing lip in sliding frictional contact with part of the second ring. The slewing bearing further includes a guiding ring axially arranged between the two seals. The guiding ring provides a flange that prevents the reversion of one sealing lip, and an annular axial collar that radially blocks the annular heel of the other seal in a radial outwards direction.