Detector modules, detectors and medical imaging devices are provided. One of the detector modules includes: a support and a plurality of detector sub-modules arranged on the support along an extension direction in which the support extends. Each of the detector sub-modules has a first area and a second area in the extension direction. A detecting device is disposed in the first area, and a functional module is disposed in the second area. The functional module is electrically connected to the detecting device for receiving an electrical signal from the detecting device. The plurality of detector sub-modules includes a first detector sub-module and a second detector sub-module that are arranged adjacent to each other in the extension direction, and the first area of the first detector sub-module at least partially overlaps with the second area of the second detector sub-module.