We report a size-manipulable synthesis of single-crystalline nanorods/nanowires of barium manganite (BaMnO3) and barium titanium manganite (BaTi1/2Mn1/2O3) by using the composite-hydroxide-mediated approach. The synthesis cleanly yields nanorods with a hexagonal perovskite structure. Typical nanorods have widths ranging between 50 and 100 nm, and the lengths can be easily controlled by time and temperature or by adding a small amount of water during the synthesis process. Resistance measurement shows that a phase transition happened at 58 K on BaMnO3. The photoluminescence spectrum of BaTi1/2Mn1/2O3 presents two emission peaks at wavelengths of 465 and 593 nm, corresponding to blue and green fluorescence. The ability to synthesize nanorod manganites of a desired length should enable detailed investigations of the size-dependent evolution of magnetism, magnetoresistance, nanoscale phase separation, and realization of a nanodevice of magnetic sensors.