Fabrications of one-dimensional (1D) nanostructures and magnetic/semiconducting heterostructures have recently been the limelight of study to establish functional nanodevices with their size and dimensionality influencing the material properties of a system. In this regard, Cr substituted ZnO nanorods were prepared under low-temperature conditions and their optical property studies have been investigated. X-Ray diffraction and magnetic measurements revealed the specimens to be composed of wurtzite phase and ferromagnetic character, respectively. Morphological features of the ZnO: Cr magnetic semiconductors have been studied to be of rod forms from the field emission scanning electron microscopy and transmission electron microscopy results. UV-vis diffused mode absorbance measurements provides enough evidence to tune the band gap of ZnO based nanomaterials through Cr incorporation, with a typical blue shift in the spectrum due to the increase in carrier concentration. Modifications in the intensity of E₂ (high) mode and sub-band edge emissions provides enough evidence for the existence of intrinsic defects associated with the O atoms, that has been reasoned for the observed ferromagnetism.