Cloud technology is an emerging distributed computing paradigm. It provides Cloud consumers with on-demand computing, storage, and networking resources. A Cloud Resource Broker (CSB) acts as a mediator between cloud consumers and cloud providers. It effectively handles application requests and efficiently allocates cloud resources. Generally, CSB encounters large volumes of application requests. It is essential to properly and evenly distribute these application requests between the available cloud resources. The proposed work introduces a Particle Swarm Optimization (PSO) based load balancing technique, which distributes cloud consumer application requests in an optimal and balanced manner. In addition, the present study investigates the Software-Defined Networking (SDN) cloud infrastructure, which dynamically configures and provides network paths on-demand, based on the network load. The proposed system is simulated and tested on real-world application traces. The proposed PSO based load balancing mechanism is shown to minimize average application response time, while maximizing throughput, cloud consumer satisfaction value, and resource utilization.