A thermal management system for a vehicle may include: a cooling apparatus including a radiator, a first water pump, a first valve, and a reservoir tank connected through a coolant line; a battery cooling apparatus including a battery coolant line connected to the reservoir tank through a second valve, and a second water pump and a battery module connected through the battery coolant line; a chiller provided in a branch line connected to the battery coolant line through the second valve and connected to a refrigerant line of an air conditioner through a refrigerant connection line; and a heating circuit including a heater connected to the coolant line and the branch line through first and second connection lines.