A slewing bearing providing a first ring, a second ring, the first and second rings being in relative rotation around a rotation axis, and at least one row of rolling elements arranged between the rings. The slewing bearing is further provided with a sealing device including at least one seal having an annular heel fixed to the first ring, and a sealing lip in sliding frictional contact with the second ring, and a deflector mounted to a lateral surface of second ring and having a deflecting part that at least partially radially surrounds the sealing lip.