The synthesis of three-dimensional carbon nanostructures without templates remains a substantial challenge. The present research enables skillfully generating horizontally-aligned carbon-nanorod-arrays (HA-CNRA), using microwave plasma-enhanced chemical vapor deposition (MW-PECVD) on quartz substrates coated with Co catalyst layers annealed at diverse temperatures. In this method, a gas mixture comprising C2H2, H2, and CO2 was used for the CNRA growth at a low substrate temperature of ∼300 °C. Electron-microscopy observation confirms the autonomous growth of individual hollow CNRs. A discernible peak at 1340 cm−1, G band peak at 1596 cm−1, and 2670 cm−1 peak (2D band) were observed, indicating a well-graphitized feature of the CNRs, which was further ascertained by the corresponding X-ray diffraction planes of (002) and (101) orientations. In the optimally grown film, a homogeneous array of nanorods with an average diameter of ∼450 nm was obtained. The C 1s spectra peaked at 284.6 eV confirming the presence of crystalline sp2-hybridized nanorods. The novelty of the work lies in enabling the Co catalyst-assisted template-free growth of HA-CNRA by low-temperature MW-CVD, utilizing the reactant atomic species like H and O from the (C2H2 + H2 + CO2)-plasma and preserving the growth continuity through a specific shadow masking configuration deployed atop the developing plane, thereby inducting a diffuse plasma on the substrate and restricting the direct collision of energetic particles with the developing network. Due to the adjustable size, shape, and advantageous architectural characteristics, horizontally-aligned CNRA manifests significant potential as electrode materials for energy storage applications, specifically in batteries and electrochemical capacitors.