This critical review focuses on Engineered nanoparticles (ENPs) types, properties, toxicities, applications, and future scopes. ENPs are specially designed chemical substances or materials with a particle size between 1 and 100 nm in at least one dimension, while the term Engineered nanomaterials (ENMs) is used collectively for ENPs and nanostructured materials. They can be classified into different classes based on their properties, shapes, or sizes. The different groups include fullerenes, metal NPs, ceramic NPs, and polymeric NPs. NPs possess unique physical and chemical properties due to their high surface area and nanoscale size. NPs like carbon nanotubes (CNTs), quantum dots (QDs), fullerenes, nanocomposites, metal-oxide nanoparticles (TiO2, ZnO, and iron oxides), and fibrous nanomaterials (NMs). Exposure to such ENP increases as nanotechnology advances, though it is an emerging field with a wide range of applications as an interdisciplinary, integrated science with huge potential. Aims to present a comprehensive review of nanotoxicity to human health and impact on the environment, future aspects breakthrough opportunities. Nanowaste as a new and challenging research topic is also highlighted. NPs’ intensive use, persistence, and retention in the environment need to evaluate nanogenotoxicity to humans and other organisms. ENMs used in therapeutic targeted drug delivery, their toxicokinetic, surface chemistry, mechanism of cellular interactions, effect on chromosomes, and DNA started being studied by researchers, however, not fully understood. Nano genotoxicity assessment should be done thoroughly following regulatory guidelines in order to safeguard humans from its harmful effects like cancer and reduce fertility. ENM retention time in the environment should be traced keeping in mind Eco nanotoxicity, bioaccumulation, and biomagnification in aquatic and forest ecosystems. The unique properties of NPs can be utilized fully by knowing all useful characteristics for breakthrough inventions in health care, cancer treatment, anti-aging (longevity), aeronautics, illuminating diodes, nanofertilizers and Artificial Intelligence (AI)-powered robotics for noble innovations for human use. Finally, the challenges of nanowaste management and gaps in breakthrough opportunities are highlighted to reflect the need for more serious action and advancement in nanoscience with novel inventions.