The title compound, [Fe(C64H64N8O4)Cl], is a five-coordinate square-pyramidal porphyrin complex with a chloride ion in the axial position, being coordinated from the protected side of the porphyrin; the FeIII atom is displaced by 0.474 (5) Å from the 24-atom mean plane of the porphyrin core towards the chloride. The porphyrin moiety is a `picket-fence' 5,10,15,20-tetrakis[2-(2,2-dimethylpropanamido)phenyl]porphyrinate (por) group. The Fe—Cl bond length is 2.221 (2) Å and the Fe—N(por) bond lengths are in the range 2.043 (5)–2.063 (5) Å. The supramolecular architecture of the crystal is sustained by C—H...O interactions between the pyrrolic and phenyl H atoms of one molecule and the carbonyl O atoms of the 2,2-dimethylpropanamido groups of adjacent molecules. The methyl groups of three of the four tert-butyl substituents exhibited rotational disorder over two positions. The investigated crystal was twinned by a twofold rotation about the (001) axis with a refined twin ratio of 0.4086 (16).