Nanostructured photocatalysts with high activity are sought for solar production of hydrogen. Spinel semiconductors with different nanostructures and morphologies have immense importance for photocatalytic and other potential applications. Here, a chemically stable cubic spinel nanostructured CdIn2S4 prepared by a facile hydrothermal method is reported as a visible-light driven photocatalyst. A pretty, marigold-like morphology is observed in aqueous-mediated CdIn2S4, whereas nanotubes of good crystallinity, 25 nm in diameter, are obtained in methanol-mediated CdIn2S4. The aqueous- and methanol-mediated CdIn2S4 products show excellent photocatalytic activity compared to other organic mediated samples, and this is attributed to their high degree of crystallinity. The CdIn2S4 photocatalyst gives quantum yields of 16.8 % (marigold-like morphology) and 17.1 % (nanotubes) at 500 nm, respectively, for the H2 evolution reaction. The details of the characteristics of the photocatalyst, such as crystal and band structure, are reported. Considering the importance of hydrogen energy, CdIn2S4 will be an excellent candidate as a catalyst for “photohydrogen” production under visible light. Being a nanostructured chalcogenide semiconductor, CdIn2S4 will have other potential prospective applications, such as in solar cells, light-emitting diodes, and optoelectronic devices.