A fabrication method for fabricating a floor mat, in particular for protecting an original equipment mat of a motor vehicle, the method being characterized in that it comprises the following steps: a) providing a flexible panel having opposite inside and outside faces (1a, 1b) and cutting it to a determined shape; b) providing an opening (2, 3, 4, 5) in said flexible panel, the outline (2a, 3a, 4a, 5a) of said opening (2, 3, 4, 5) being defined by an intermediate edge arranged between inner and outer edges (11, 12); c) providing a mold having a bottom from which there projects at least a first partitioning element (20, 21, 22, 23) having a top, said first partitioning element (20, 21, 22, 23) defining a determined inside volume (20a, 21a, 22a, 23a); d) placing said flexible panel in the mold, said flexible panel and said partitioning element (20, 21, 22, 23) being arranged in such a manner that the outer and inner edges (12, 11) project at least in part respectively inside and outside said inside volume (20a, 21a, 22a, 23a), the intermediate edge bearing at least in part against the top of the first partitioning element (20, 21, 22, 23); e) providing a backing mold arranged in such a manner as to co-operate with said mold and pinch the intermediate edge against the top of said first partitioning element (20, 21, 22, 23); and f) injecting at least one polymer in the molten state into said inside volume (20a, 21a, 22a, 23a) via distribution means arranged inside the mold and the backing mold so as to overmold said outer edge at least in part and fill in said opening (2, 3, 4, 5) in full or in part by forming an overmolded portion (13, 14, 15, 16) emerging in the inner and outer faces (1a, 1b) of the flexible panel. a) providing a flexible panel having opposite inside and outside faces (1a, 1b) and cutting it to a determined shape; b) providing an opening (2, 3, 4, 5) in said flexible panel, the outline (2a, 3a, 4a, 5a) of said opening (2, 3, 4, 5) being defined by an intermediate edge arranged between inner and outer edges (11, 12); c) providing a mold having a bottom from which there projects at least a first partitioning element (20, 21, 22, 23) having a top, said first partitioning element (20, 21, 22, 23) defining a determined inside volume (20a, 21a, 22a, 23a); d) placing said flexible panel in the mold, said flexible panel and said partitioning element (20, 21, 22, 23) being arranged in such a manner that the outer and inner edges (12, 11) project at least in part respectively inside and outside said inside volume (20a, 21a, 22a, 23a), the intermediate edge bearing at least in part against the top of the first partitioning element (20, 21, 22, 23); e) providing a backing mold arranged in such a manner as to co-operate with said mold and pinch the intermediate edge against the top of said first partitioning element (20, 21, 22, 23); and f) injecting at least one polymer in the molten state into said inside volume (20a, 21a, 22a, 23a) via distribution means arranged inside the mold and the backing mold so as to overmold said outer edge at least in part and fill in said opening (2, 3, 4, 5) in full or in part by forming an overmolded portion (13, 14, 15, 16) emerging in the inner and outer faces (1a, 1b) of the flexible panel.