A low-bulkiness hinge for closing a closing element anchored to a stationary support structure, such as a wall, a frame or a floor includes a hinge body which includes a longitudinal operating chamber defining a first axis, a pivot coupled to the hinge body to rotate around a second axis between the opening and closing positions of the closing element, and a slider slidable in the operating chamber along the first axis. The operating chamber has a first seat for the pivot and a second seat for the sliding of the slider, which includes a shaft and an operative head that are mutually coupled. The hinge body has a first opening for inserting, perpendicularly to the first axis, the operative head into the second seat and a second through opening for inserting, coaxially to the first axis, the shaft into the housing. The hinge further has the shaft and the operative head fixed to one another after insertion in the second seat (so as to form a unitary assembly integrally slidable along the first axis.