SARS-CoV-2 utilizes its main protease (Mpro) to generate functional proteins from polyproteins for successful replication in host cells. This has led to a significant interest in developing pharmacological agents for targeting Mpro, and therefore, tools allowing the monitoring of its activity in live cells is in demand. Here, we plan to engineer cost effective, next-generation, BRET-based biosensors for monitoring proteolytic activity in live cells and in vitro possessing a higher sensitivity, enabling detection of Mpro activity at low concentrations.