A unit for forming absorbent sanitary articles including a drum rotatable about its axis of rotation and having a circumferential peripheral surface movable along a feed direction, first feeding means for feeding a succession of pairs of panels of material facing the circumferential peripheral surface and configured to position each pair in such a way that the respective two panels are facing each other and transversely aligned with the feed direction and second feeding means for feeding a continuous web of material suitable for defining at least part of the main body of an absorbent sanitary article, and configured to position the web on the circumferential peripheral surface of the drum in such a way that each panel projects partly sideways from the web. The unit comprises an ultrasonic sealing station located along the circumferential peripheral surface of the drum, in a zone located operatively downstream of the second feeding means, and configured to attach each panel of the pair to the web at at least one plurality of sealing points arranged in succession along the feed direction.