A car seat alarm system including a weight-sensor plate assembly, a power source, a dashboard sensor, and a portable device including a speaker. The weight-sensor plate assembly is positioned and configured to detect a weight of a child in a car seat. The weight-sensor plate assembly is in communication with the dashboard sensor including a transceiver. The dashboard or visor sensor is configured to communicate that a child is present within the car seat. The dashboard sensor is in wireless communication with the portable device such as a key fob or smartphone. The dashboard sensor is configured to activate an alarm through the speaker when the portable device extends past a pre-determined proximity range from the dashboard sensor is reached and if the weight of the child is present within the car seat.