Strong and effective authentication methods are more important than ever in the ever-changing field of cybersecurity. In this work, a Mobile One-Time Password (OTP) Authentication Protocol designed for local federated clients utilizing the Message Queuing Telemetry Transport (MQTT) protocol to communicate with a federated central server is designed and implemented. This protocol strengthens the security foundation of federated systems by ensuring the safe and dependable delivery of OTPs while utilizing the lightweight and effective characteristics of MQTT. The suggested protocol tackles the scalability, security, and latency issues that come with federated setups. We show how the protocol can effectively mitigate possible security threats, like replay attacks and illegal access, while maintaining user convenience through a thorough analysis and implementation. Our protocol strikes a balance between security and performance, according to experimental results, which makes it a workable answer for modern federated authentication requirements.