The self-drilling and slotting fastener with retainer has a thin retainer wire that is used to bring the flat nut portion that is inserted through a wall into position with the hole in the wall for a screw to mate with the threads in the nut. The nut has a rectangular body shape with a thin elongated section extending from away from one side. This elongated section has a drilling point and serrated teeth for making a slot. It looks almost like a car key. The drilling point makes a hole wide enough for the matting screw and is long enough to go completely through the wall. The serrated teeth on the elongated section are used to make horizontal slots on each side of the hole to accommodate the narrow width of the nut body. The resulting slotted hole is clean and provides a smooth and uniform surface on the inner surface of the wall for the nut to rest against. The drilling & sawing section is crimped at the juncture with the body and has a hole in it for being put on the retaining wire. After the hole and slot is made in the wall the elongated section is broken off and put on the retainer wire so it keeps the nut from falling inside the wall. The nut is put into position over the hole by pulling on the cord. The rectangular flat nut then rests against the inside surface of the wall and has a wide area for holding the object. This provides an improvement in holding capacity for this system.