A Bluetooth headset in-car holder/car kit has a main body having an end formed into a pivoted plug for plugging in a cigarette lighter on a vehicle to obtain a power supply, and another end into a holding seat for a wireless Bluetooth headset to seat therein. The holding seat is provided with at least one connecting port, such as a USB port, to electrically connect to the Bluetooth headset and the plug, so that power is supplied from the vehicle via the plug to charge the Bluetooth headset. The main body is provided with speaker and microphone electrically connected to the connecting port, so that the headset in-car holder car kit with the wireless Bluetooth headset seated therein forms an in-car Bluetooth handsfree kit, enabling a user to listen and speak via the speaker and the microphone on the main body without putting on the Bluetooth headset.