The unique architectures of semiconductor quantum dots (QDs) and one-dimensional (1D) nanostructures give rise to a fascinating array of optical and electronic properties, making them useful for numerous industrial and environmental applications. This work reports the latest developments in QD-based nanotechnologies featuring II–VI semiconductor nanostructures with tunable optoelectronic properties. The synthesis of chalcogenide-, oxide-, and alloy-based semiconductor QDs is described in detail. Special attention is given to optical investigations supplemented by density functional theory calculations to explore the energy levels and electronic structure of II–VI semiconductor QDs. Finally, new applications of QDs in the areas of solar cells and optoelectronics are summarized, and the work concludes an assessment of future prospects of II–VI semiconductor QDs and 1D nanomaterials.