Securing data transmission in Internet of Things (IoT) environments is critical due to the resource constraints of edge devices and the sensitivity of transmitted data. This paper proposes an enhanced security framework based on a lightweight variant of the Rivest Cipher 4 (RC4) algorithm, designed for end to end encryption in IoT ecosystems. Sensor nodes collect environmental data and apply enhanced RC4 encryption before transmitting it to a Raspberry Pi broker over MQTT. The broker securely forwards the encrypted data to Google Cloud Firestore via HTTPS. Cloud Functions then decrypt the data for real-time visualization and insights using Looker Studio. The experimental results show that the enhanced RC4 method provides low memory usage, strong data integrity, and reduced power consumption while accepting slightly higher encryption latency to achieve improved security. Frequent key rotation adds a layer of protection, making the framework well suited for resource constrained IoT applications requiring secure data communication.