An apparatus for heat-sealing a lidding film to a supporting element on which a product is present, the apparatus comprising: a structure; a movement track which is fitted on the structure and which extends between an infeed zone and an outfeed zone; a heat-sealing device which is fitted on the structure, along the movement track, and which comprises a supporting unit and a closing unit; at least one of the supporting unit and the closing unit being movable, relative to the other, between a home position in which they are at a distance from each other, and an operating position in which the supporting unit and the closing unit are coupled to clamp, in use, the lidding film and a supporting element; a conveying unit which is configured to support the supporting element and is associable with the movement track for moving on it, conveying the supporting element, from the infeed zone to an intermediate zone at which the heat-sealing device is located, and from the intermediate zone to the outfeed zone; wherein: the conveying unit defines a seat for the supporting element and comprises one or more active portions configured to support from below the supporting element positioned in the seat; and when the conveying unit is located in the intermediate zone, during an activation of the heat-sealing device the one or more active portions couple to the supporting unit to define with it a clamping unit for clamping the supporting element against the closing unit. a structure; a movement track which is fitted on the structure and which extends between an infeed zone and an outfeed zone; a heat-sealing device which is fitted on the structure, along the movement track, and which comprises a supporting unit and a closing unit; at least one of the supporting unit and the closing unit being movable, relative to the other, between a home position in which they are at a distance from each other, and an operating position in which the supporting unit and the closing unit are coupled to clamp, in use, the lidding film and a supporting element; a conveying unit which is configured to support the supporting element and is associable with the movement track for moving on it, conveying the supporting element, from the infeed zone to an intermediate zone at which the heat-sealing device is located, and from the intermediate zone to the outfeed zone; wherein: the conveying unit defines a seat for the supporting element and comprises one or more active portions configured to support from below the supporting element positioned in the seat; and when the conveying unit is located in the intermediate zone, during an activation of the heat-sealing device the one or more active portions couple to the supporting unit to define with it a clamping unit for clamping the supporting element against the closing unit. the conveying unit defines a seat for the supporting element and comprises one or more active portions configured to support from below the supporting element positioned in the seat; and when the conveying unit is located in the intermediate zone, during an activation of the heat-sealing device the one or more active portions couple to the supporting unit to define with it a clamping unit for clamping the supporting element against the closing unit.