Growing security challenges in residential and industrial spaces demand access control systems that are both reliable and user friendly. Conventional methods such as keys, cards, and passwords are vulnerable to loss, duplication, and misuse. To address these limitations, this paper proposes a smart security system that combines smartphone-based fingerprint authentication with IoT technology. User verification is carried out on the mobile device, and a secure wireless command is transmitted to an ESP8266 microcontroller to operate a relay-controlled solenoid lock. Since biometric data is processed locally on the smartphone, the system enhances privacy while eliminating the need for physical keys or external fingerprint modules. The proposed approach offers a secure, economical, and scalable solution suitable for smart homes, offices, and restricted access areas