This research provides the design, development, and evaluation of an affordable smart agriculture system using an Arduino Uno microcontroller. The system includes real-time environmental monitoring—temperature, light intensity, and soil moisture—coupled with a local security aspect. A digital temperature sensor, e.g., the DHT11, and a Light Dependent Resistor (LDR) measure the ambient conditions, while a soil moisture sensor measures the moisture levels in the soil. An automatic cooling fan, regulated by a relay module, is powered to mitigate excessive temperature, thereby providing an ideal microclimate. In the security aspects, an Infrared (IR) sensor detects illegal access, which causes an alarm through a buzzer. Experimental verification verifies the system performance in providing favorable environmental conditions while issuing timely alerts for illegal access. This combined approach offers a realistic and general solution for small to medium-scale agribusinesses, thus improving crop management and farm security.