A three-dimensional billboard display system features a flexible sheet of banner material having displayed content on a display side thereof, and a two-dimensional footprint area on the display side that is discretely identifiable from the displayed content. A flexible cover fastened to the flexible sheet in a position overlying the two-dimensional footprint area on the display side and enclosing a three-dimensional space between said cover and said flexible sheet. One or more inserts form a three-dimensional body of predetermined shape inside the three-dimensional space, the flexible cover spanning in taut condition over the three-dimensional body, thereby imparting the predetermined shape to the three-dimensional space and imparting the flexible cover with a three-dimensional form bulging outwardly from the display side of the flexible sheet. A reinforcement layer features a mesh or netting of criss-crossing webbing straps on a backside of the flexible sheet to carry the weight of the 3D embellishment.