API gateways play a significant role in application integrations by acting as a single entry point for managing API traffic. They streamline communication between different services and applications, facilitating access control, rate limiting, and security protocols. API gateways enhance performance and reliability by caching responses and load balancing requests. Additionally, they simplify the development process for API consumers, providing uniform access to multiple underlying services. Overall, they are essential for efficient, secure, and scalable API management in modern software architectures.