Transition metals and metal oxide nanostructures are promising materials owing to their unique physical and chemical properties such as thermal stability, rigidity, and high chemical resistance. These properties enable them to be utilized for a wide range of environmental and biological applications; including antibacterial and photocatalytic activities etc. This led various research groups to develop several techniques for the synthesis of metal nanomaterials with different sizes, shapes and morphologies. However, it is still desirable to develop new environment-friendly synthetic processes to prepare these nanomaterials with new textural forms for their viable applications. In this regard, a very simple, fast, cost-effective and toxic free self-designed Atmospheric Pressure Microplasma (AMP) technique has been developed for the synthesis of metals (Ag and Au) and metal oxides (ZnO and CuO) nanostructures. In addition, several analytical techniques were used to study the morphological, structural, optical and compositional properties of the synthesized nanostructures. Furthermore, the prepared noble metal (Au and Ag) nanostructures were used for antibacterial applications while the metal oxide (ZnO and CuO) nanostructures were used for both antibacterial and photocatalytic applications. Scanning electron microscopy (SEM) showed the sheet-like structures of Ag and spherical structures for Au. However, a change in lateral dimension has been observed with the increase in the precursor’s concentration. XRD showed highly crystalline nature and single phase (fcc symmetry) of the as-synthesized Ag and Au nanostructures. In addition, highly crystalline ZnO nanostructures (nanosheets, nanodrums, and nanoneedles) were synthesized in the presence of different ionic (anionic and cationic) surfactants and nonionic fructose. It was found that the fructose and surfactants greatly influenced the morphology of synthesized ZnO nanostructures. Similarly, highly crystalline sheet-like CuO nanostructures were also synthesized without using any surfactant. SEM of CuO confirmed the variation in the dimensions of nanostructures with precursor’s concentration. XRD showed the hexagonal (wurtzite structure) phase of ZnO and monoclinic phase of CuO. The antibacterial tests of all the synthesized nanomaterials were evaluated against several bacterial strains. Results suggested that all the nanostructures exhibited effective bactericidal activity against all tested strains. It was observed that the antibacterial activity of the prepared samples not only depends upon the shape of nanostructures, but also on the type of the bacteria. This study also demonstrates the photocatalytic activity of the assynthesized ZnO and CuO samples for the degradation of organic dyes under direct sunlight. Results indicated that the ZnO and CuO sheet-like photocatalysts exhibited significant photocatalytic activities against tested dyes after 80 minutes of sunlight illumination. The findings of this research work may prove helpful in contributing towards new studies conducted on applications involving catalysis, optoelectronic devices, biomedical, pharmaceutical, environmental bioremediation and so forth.