Nanomaterials, in the twenty-first century, have become a daily necessity owing to their unique chemical, biological, and physical properties. It has become an emerging technology in the field of science today. Despite their vast positive impact on science and technology, they pose environmental threats due to their minute size and high reactivity. This chapter will address the environmental impact of nanomaterials and their safety. Their advantages and disadvantages in the environment, food, textile, medicine, electronics, and many more, will be addressed. It will also shed light on the pros and cons of nanomaterials in human health and ecosystem. In addition, the best way to use nanomaterials and their preparation will be addressed. This chapter also aims to offer a balanced perspective on the benefits and challenges associated with nanomaterials.