I-Design is a personalized interior designer that leverages large language models (LLMs) to generate and visualize 3D interior designs based on natural language user input. The system consists of a team of LLM agents that engage in dialogues and logical reasoning to transform textual user preferences into feasible scene graphs, which are then used to determine optimal object placements within the scene. An effective placement algorithm ensures that objects are placed correctly within the scene, and 3D assets are retrieved from an existing database to construct the final design. The evaluation protocol, which utilizes a vision-language model, complements the design pipeline. Extensive experiments show that I-Design outperforms existing methods in delivering high-quality 3D design solutions that align with user preferences, demonstrating its effectiveness in generating detailed and conceptually faithful interior designs.I-Design is a personalized interior designer that leverages large language models (LLMs) to generate and visualize 3D interior designs based on natural language user input. The system consists of a team of LLM agents that engage in dialogues and logical reasoning to transform textual user preferences into feasible scene graphs, which are then used to determine optimal object placements within the scene. An effective placement algorithm ensures that objects are placed correctly within the scene, and 3D assets are retrieved from an existing database to construct the final design. The evaluation protocol, which utilizes a vision-language model, complements the design pipeline. Extensive experiments show that I-Design outperforms existing methods in delivering high-quality 3D design solutions that align with user preferences, demonstrating its effectiveness in generating detailed and conceptually faithful interior designs.