A dimming and CCT tuning system comprises a controller and multiple LED-based lighting devices. Each lighting device comprises a control circuit, at least two LED driving circuits, and at least two types of LED-based light sources. When the controller receives the dimming and CCT tuning signals from its inputs, it generates a modulated dimming and CCT tuning signal portion in the AC voltage delivered to the multiple lighting devices. Afterwards, a regular AC power is delivered. In receiving, each lighting device demodulates such signal portion and generates at least two control signals to the at least two LED driving circuits which then individually power the at least two types of LED-based light sources to emit desired light levels and CCTs. The system eliminates extra wires required in 0-10 V dimming control and maintains an undistorted AC waveform in most of operating time, not like a TRIAC dimming.