A seatback assembly structured to at least partially support a seated individual on a wall, specifically but not exclusively, a pre-existing or newly constructed wall configured to facilitate one or more individuals to sit on an exposed portion thereof. The seatback assembly includes a back support orientation to and extending along the length of the wall and a connector assembly disposed in an operative position interconnecting the back support to the wall. The connector assembly includes at least one or a plurality of brackets, each including a base and a support segment and an anchor interconnecting each of the one or more brackets at least partially on the interior of and in stabilizing relation to the wall. A supporting orientation of the back support includes it connected to the wall in receiving, engageable relation to a seated individual.