Maintaining optimal indoor humidity is essential for human comfort, health, and the safety of electronic devices. Conventional humidifiers lack intelligent monitoring and safety mechanisms, and typically require manual operation. This paper presents the design and implementation of a Smart Room Humidifier using the ESP32 microcontroller. The system continuously monitors ambient humidity using a DHT11 sensor and automatically controls a 5 V ultrasonic mist maker through a transistor-driven switching circuit. A water level sensor prevents dry operation, and a buzzer alerts the user when the water level is low. The ESP32’s built-in Wi-Fi module enables web- based remote ON/OFF control, while a 0.96-inch OLED display provides real-time readings of humidity, temperature, water level status, and system state. The system is powered by a 5 V buck converter; regulated 3.3 V for sensor modules is supplied directly by the ESP32. Experimental testing confirms reliable performance, safe operation, and effective humidity control. The system is low-cost and well-suited for indoor domestic applications.\n