The title compound, [Mn(C₁₈H₁₈N₂O₄)(C₇H₅O₃)(H₂O)], was synthesized by a template reaction of ethane-1,2-diamine and 3-methoxy­salicylaldehyde in presence of manganese(II) 4-hydroxy­benzoate. The Jahn–Teller-distorted manganese(III) centre has an octa­hedral geometry. Extensive O—HO hydrogen-bonding inter­actions generate a two-dimensional sheet structure parallel to (103).