In this review, we provide an overview of the nanopaper biosensors used for point of care (POC) diagnostics in various fields such as biomedical, environmental, food safety, and agriculture. The lateral flow assays (LFAs) comprising nanoparticles have drawn the interest of researchers due to their high sensitivity, low cost, lower time consumption, lack of equipment, and easy handling characteristics. These assays have become an integral part of the health sector all over the world over a short time period and are extensively being engaged in diagnosis of viral infections in regions low on resources. A large number of innovative approaches have been introduced in making these test-strips or nanopaper biosensors as quickly as possible, because of their ease of operation, cheaper cost, and quick results, even with the simplest setups or in pathological laboratories, etc. Keeping all this in mind, we have reviewed the nanoparticles based lateral flow test strips (LFTS), their composition, working methods, reaction mechanisms, detection methods, and applications in different fields. We also provide an overview of paper-based microfluidic analytical devices (μPADs) and our perspective about the future trends which may facilitate understanding their applications.