CCERT is a 68kDa cytosolic protein, that transfers ceramide from the endoplasmic reticulum (ER) to the trans-Golgi network (TGN).1 Once in the TGN, ceramide functions as the precursor for the synthesis of more complex sphingolipids like sphingomyelin, which is a major component of mammalian plasma membrane. Upregulation of CERT protein has been associated with various pathological conditions like cancer, viral infections (i.e. Hepatitis C), neurodegenerative diseases (i.e., Alzheimer’s and Parkinson’s disease). Additionally, gain-of-function mutations in CERT have been linked to intellectual disability. Therefore, CERT protein is considered as a promising drug target. We have developed a novel cell-based assay that allows for the direct monitoring of CERT activity in cells.2 This innovative method overcomes the limitations of previous approaches, which could only measure CERT activity indirectly. Our assay is based on a genetically encoded BRET-based biosensor, in which Nanoluciferase was fused to the CERT protein for resonance energy transfer to a Nile red-labeled ceramide, which is either directly bound to CERT or transported to the adjacent Golgi membrane. Our assay is suitable for high-throughput screening of CERT inhibitors, allowing the direct in cellulo assessment of CERT binding and inhibition. It features an easy setup and its utility was demonstrated through the screening of a library of 140 derivatives of the well characterized CERT inhibitor HPA-12. Screening of the library identified six compounds that outperformed HPA-12 in both subsequent dose-response studies and in the orthogonal lipidomics analysis. Finally, the underlying principle of the assay can be extended to other lipid-transfer proteins, offering broader applicability for similar research.