Chip-on-board (COB) modular lighting systems and methods of manufacture are described herein. A system includes a COB assembly including a thermally conductive plate and a COB light-emitting diode (LED) device thermally coupled to the thermally conductive plate. The COB LED device includes multiple LED chips disposed on a surface of a substrate. The substrate includes first electrical power contacts exposed from at least the surface. The system further includes an electronics board that has second electrical power contacts. The electronics board is attached to the COB assembly such that the first and second electrical contacts are electrically coupled and the thermally conductive plate is attached to the electronics board.