A mixed reality developer designs, tests, and deploys immersive experiences that blend physical and digital worlds. They use programming languages and development tools to create interactive applications for mixed reality devices like Microsoft's HoloLens. Tasks include creating models, animations, and user interfaces, integrating real-world and virtual elements, ensuring user interaction and comfort, and troubleshooting any issues. They also collaborate with other team members to meet project goals, and stay updated on the latest MR technologies and trends. Their work is applied in various fields such as gaming, education, healthcare, and industrial training.