I have engineered chimeras comprising of a circularly permutated energy donor that is inserted into a HaloTag surface loop to provide high intramolecular BRET efficiency to a bound chromophore. This improved BRET efficiency can transfer more resonance energy to the acceptor than current luciferases, which emit strongly in the blue light region that is not compatible with many imaging applications. The chimera allows for a broad range of applications, specifically bioluminescent imaging in complex animal models.