The de novo construction of repeat proteins has received much attention from biologists and chemists, yet that of a β-barrel structure, one of the most well-known classes, has not been accomplished to date. Here, we report the first chemical construction of a β-barrel tertiary structure with a pore through a combination of peptide folding and metal-directed self-assembly. Coordination of zinc salts to an eight-residue peptide fragment bearing β-strand- and loop-forming sequences resulted in a β-barrel in which six-stranded cylindrical antiparallel β-sheets formed a hydrophobic pore with a specific shape.