Abstract: A seat belt alarm system to alert users to the presence of an infant or child, or disabled, infirm or elderly person in a vehicle. The seat belt alarm utilizes a portable bracket configured to removably attach to a female receptacle of a seat belt system. The bracket includes a tension mechanism positioned to be acted upon by a male buckle of a seat belt system when the male buckle of the seat belt mates with the female receptacle of the seat belt system. In a depressed state, the tension mechanism activates a signal transmitter configured to transmit a local signal received by a signal receiver integrated in a keychain fob. When the keychain fob moves outside of a signal range (e.g., 10 feet) while the tension mechanism remains in a depressed state, an alarm and/or red indicator light on the keychain fob is/are activated.