Bioluminescent biosensors useful for monitoring and/or quantifying, in vitro or in vivo, activity of the Hippo signaling pathway. The biosensors monitor LATS kinase activity or YAP-TEAD interaction. The biosensors may be used in methods for monitoring and/or quantifying in real-time, in vitro or in vivo, activity of the Hippo signaling pathway, wherein the activity may be LATS kinase activity and/or YAP-TEAD interaction. The biosensors may be provided in kits for monitoring and/or quantifying in real-time, in vitro or in vivo, activity of the Hippo signaling pathway, wherein the activity may be LATS kinase activity and/or YAP-TEAD interaction.