A transcatheter atrio-ventricular valve prosthesis for functional replacement of an atrio-ventricular valve in a connection channel, having a circumferential connection channel wall structure, between atrial and ventricular chambers of a heart, including an inner device to be disposed in the interior of the connection channel, the inner device having a circumferential support structure which is radially expandable and having a valve attached to the circumferential support structure, and an outer device to be disposed on the exterior of the connection channel, wherein the outer device at least partly extends around the inner device at a radial distance to the inner device, wherein the inner and outer devices form a securing mechanism for securing the circumferential connection channel wall structure therebetween.