Assembly for unlocking the door of vehicles, of the type of vans, trucks, lorries, semi-trailer trucks, trailers and the like, comprising a base which, in use, is stably coupled to the door and a handle which is U-shaped and has two parallel arms connected at one end by an ergonomic cross-member for being gripped by a user to rotate the handle and cause unlocking of the door, the ends of said arms, opposite to said cross-member, being fixed to at least one bar, which, in use, is coupled in a rotatable manner to the door and which rigidly supports at mutually opposite ends thereof respective means of anchoring to the frame of the vehicle, said handle being rotatable at least from a secured configuration, in which it is substantially facing and proximate to said base and said anchoring means can be engaged with the frame of the vehicle, to at least one released configuration, in which it is at least partially lifted from said base and said anchoring means can be disengaged from the frame of the vehicle, in order to allow the free rotation and the opening of the door, and vice versa, said base being coupled in a rotatable manner to a button, which is moveable at least between a first angular position, in which it is elastically kept in interference with the rotation of said handle, and a second angular position, in which it is disengaged from said handle, the assembly further comprising a securing body, which is moveable at least between a first angular configuration, in which, independently of said button, it is elastically kept in interference with the rotation of said handle, and a second angular configuration, in which it is disengaged from said handle, said securing body being a rocker arm which is actuated to rotate by said button between said first angular configuration and said second angular configuration, said rocker arm comprising a central block, which is articulated to said base at a first pivot, a tooth extending from said central block and abutting against an elongated protrusion of said button, for the raising of said tooth as a consequence of the rotation of said button from said first angular position to said second angular position, with consequent forced rotation of said rocker arm from said first angular configuration to said second angular configuration, said rocker arm further comprising an extension, extending from said central block on the side opposite to said tooth, said extension forming a shoulder which is kept elastically in abutment, in said first angular configuration, against a first flank of a transverse band of said handle, in order to obstruct the rotation of said handle, at least one first spring being wound around said first pivot, the elastic reaction of said at least one first spring keeping said shoulder in abutment against said first flank, and said rocker arm in interference with the rotation of said handle, said button comprising a central body, which is articulated to said base at a second pivot, a tab extending from said central body, on the side opposite to said protrusion, and supporting an abutment plate, for the manual actuation of said button, in said first angular position an edge of said tab being kept elastically resting on a respective second flank, which is opposite to said first flank, of said transverse band, in order to obstruct the rotation of said handle, at least one second spring being wound around said second pivot, the elastic reaction of said at least one second spring keeping said edge of said tab resting against said second flank, and said button in interference with the rotation of said handle.