The security challenges being encountered in many places today require electronic means of controlling access to secured premises in addition to the available security personnel. Various technologies were used in different forms to solve these challenges. The Radio Frequency Identification (RFID) Based Access Control Security system with GSM technology presented in this work helps to prevent unauthorized access to controlled environments (secured premises). This is achieved mainly through the use of a Radio Frequency Identification System with operating frequency of 125 KHz, Microcontroller programmed to send control signals, DC motor, relay, buzzer, Liquid Crystal Display (LCD) and GSM/GPRS Modem. Once the RFID tag which contains the user’s unique information is scan by the RFID reader and confirmed match with the information stored in the microcontroller, the microcontroller is instructed to turn ON the DC motor through L293D driver, display “USER NUMBER and CARD NUMBER” on the LCD and activates the GSM/GPRS modem to send SMS alert “AUTHORIZED, valid RFID card shown, User is allowed to enter, user number” to security personnel. Else, the DC Motor remained OFF, LCD displays “READ RFID CARD NOT VALID”, buzzer turns ON for about 5seconds and GSM/GPRS modem activated to send “UNAUTHORIZED, invalid RFID card is used to access the security system” to the security personnel. The electronic circuit was implemented, the codes for microcontroller were written in assembly language, debugged and compiled using the KEIL Micro vision 4 integrated development environment. The resultant Hex files were programmed into the memories of the microcontrollers with the aid of a universal programmer. Hardware simulation was carried out using the Proteus Virtual System Modelling (VSM) version 8.0. An importation implication of this paper is that the system is cheaper to maintain and more efficient in comparison with a manually operated type or key lock system. The RFID based access control system can be useful in providing security for homes, organizations, and automobile terminals to increase the level of security.