The increasing adoption of Internet of Things (IoT) technology has raised security concerns due to the computational and power constraints of embedded devices. Traditional cryptographic algorithms often impose high resource demands, making them impractical for IoT environments. This paper investigates the use of lightweight cryptographic algorithms, specifically PRESENT and SIMON, for securing data transmission in IoT applications. The implementation involves an ESP32 microcontroller interfaced with a DHT11 sensor, where the collected environmental data is encrypted before being transmitted to the cloud platform, ThingSpeak. The performance of the encryption algorithms is analyzed based on computational efficiency, memory consumption, and security strength. Experimental results demonstrate that lightweight cryptographic techniques provide an effective trade-off between security and performance, ensuring data integrity and confidentiality without significantly impacting device resources. The study highlights the importance of integrating lightweight cryptography into IoT networks to mitigate security vulnerabilities while maintaining operational efficiency. These findings contribute to the development of secure and scalable IoT systems that address the growing demand for resource-efficient security solutions.