Translating the extraordinary optoelectric properties of colloidal quantum rods (QRs) into functional devices requires multiscale structural control to preserve the nanoscale attributes as well as to introduce micro- and macroscale interactions between the building blocks. Self-assembly of anisotropic QRs into ordered nanostructures can tailor the photoelectric properties of the QRs, such as in light absorption, and charge separation and transfer. However, it remains a challenge to assemble anisotropic nanomaterial into centimeter-sized, multilayered continuous films that retain nanoscale properties in the fabricated macroscopic devices. We have developed a quasi-solid-state self-assembly of randomly oriented nanostructures for overcoming this challenge, demonstrated by the re-assembly of randomly packed ZnSe/ZnS QRs into aligned and ordered parallel monorails (PMs). These ZnSe/ZnS PMs show significant enhancement in photo-excited charge transport, boosting photocatalytic oxygen evolution rates and the enhancement of photoelectrochemical activities, with a photocurrent density of 18 μA/cm2, 5 times higher than the parent random packing of ZnSe/ZnS QRs. The ZnSe/ZnS PMs enrich the p-n heterojunctions, which can modulate charge carrier separation and transport at the interfaces. The new method has applicability for re-assembling randomly packed films of anisotropic nanoparticles into ordered nanostructures. Importantly, the extraordinary photoelectro-energy conversion behavior of the Type-I core/shell quantum materials illuminates the pathways for novel designed materials by tailoring the hierarchical structures at all scales.