Odorant receptors (ORs), recognized as the largest subfamily of G protein-coupled receptors (GPCR), are increasingly identified as membrane proteins crucial not only in nasal but also in various extra-nasal biological processes. However, researching the functions of these extra-nasal ORs is challenging due to the limited availability of ligands, posing a significant barrier to comprehensive studies. Large-scale screening with in vitro assays, such as the halide-sensitive yellow fluorescent protein (YFP) quenching assay, is crucial for deorphanizing ORs. This protocol employs the YFP quenching assay to identify OR-ligand interactions, thereby advancing OR deorphanization research.