To develop bending failure mechanics and establish the bending strength prediction models, fiberboards with both uniform and “bowl-shaped” vertical density profiles (VDPs) were manufactured, and their bend loading–deflection relations were evaluated and compared. The bending modulus of elasticity (MOE) and rupture (MOR) of fiberboards with bowl-shaped VDP (BS-fiberboard) were predicted using the sheet laminating theory. The results indicate that when fiberboards are of the same average density, the bending performance of BS-fiberboard is at least 40 percent stronger than uniform fiberboard. The MOE and MOR prediction models of BS-fiberboard correlated with thickness of panel, average density, surface density, density of sandwich layer, and thickness of sandwich layer and had a very strong predictive ability.