A modular electronic deadbolt includes a bolt module having a first housing defining a first longitudinal axis, a motor disposed in the first housing, and a deadbolt configured to be linearly moveable in relation to the first housing along the first longitudinal axis by the motor. The modular electronic deadbolt also includes a battery module configured to be operatively coupled to the bolt module. The battery module includes a second housing configured to receive a power source, and a face plate coupled to the second housing. The faceplate defines a second longitudinal axis and includes an extension that extends along the second longitudinal axis. The extension is configured to removably couple the bolt module to the battery module such that the first longitudinal axis is substantially orthogonal to the second longitudinal axis.