A heat pump system for a vehicle may include a cooling device including a radiator connected to a cooling line and a first water pump to cool an electric component; a battery module provided on a battery cooling line selectively connectable to the cooling line through a first valve; a heating, ventilation, and air conditioning (HVAC) module including an internal heater connected to the cooling line through a first connection line, a cooler connected to the battery cooling line through a second connection line, and an opening or closing door provided between the internal heater and the cooler and controlling external air passing through the cooler to be selectively introduced into the internal heater depending on cooling, heating, and heating and dehumidifying modes of the vehicle; and a centralized energy (CE) module connected to each of the battery cooling line and the cooling line.