Hierarchical architectures encompassing one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) nanostructures have garnered significant attention in energy and environmental applications due to their unique structural, electronic, and optical properties. These architectures provide high surface area, enhanced charge transport pathways, and improved light-harvesting capabilities, making them versatile candidates for next-generation photovoltaic (PV) systems. Among these, 1D structures, such as nanorods, nanowires, and nanotubes, offer distinct advantages, including anisotropic charge transport, reduced recombination rates, and enhanced light absorption due to their high aspect ratio and directional charge flow. In this focused review article, the pivotal role of one-dimensional titanium dioxide (1-D TiO