The classical working lines of analytical nanoscience and nanotechnology (AN&N) are the characterization/determination of nanomaterials and their use as tools (e.g., sorbents, inert/active supports, and sensors) for improving analytical processes. A widely discussed topic in the context of AN&N consists of the synergistic combination of these two facets in the same analytical process; that is, the determination of nanomaterials using nanoparticles of the same or different nature. This is a promising approach, named as “third way” in AN&N in this study for the first time, which is of great relevance not only in the analytical chemistry realm but also in nanoscience and nanotechnology. In this study, the definition of the “third way,” the corresponding objectives and classifications as well as the incipient state of the art of this topic are critically presented. This study also presents examples concerning the determination of nanomaterials using nanoparticles and their classification based on the nanoparticle used as tool (e.g., metallic, carbon, or hybrid nanomaterials). They have been applied for the determination of a variety of nanomaterials in environmental, biological, or food matrices, with the nanotools being involved in different steps of the analysis. The main purpose of this study is to share with the chemical community a new and promising route to extract reliable information from nanoscience and nanotechnology.