lmms-finetune is a unified codebase designed to simplify the fine-tuning process for large multimodal models (LMMs). It provides a structured framework that allows users to seamlessly integrate and fine-tune cutting-edge LMMs, supporting full fine-tuning as well as strategies like LoRA. The codebase is lightweight and straightforward, making it easy to understand and modify, and it supports various models including LLaVA-1.5, Phi-3-Vision, Qwen-VL-Chat, LLaVA-NeXT-Interleave, and LLaVA-NeXT-Video.