We present Uni3DL, a unified model for 3D Vision-Language understanding. Distinct from existing unified 3D vision-language models that mostly rely on projected multi-view images and support limited tasks, Uni3DL operates directly on point clouds and significantly broadens the spectrum of tasks in the 3D domain, encompassing both vision and vision-language tasks. At the core of Uni3DL, a query transformer is designed to learn task-agnostic semantic and mask outputs by attending to 3D visual features, and a task router is employed to selectively produce task-specific outputs required for diverse tasks. With a unified architecture, our Uni3DL model enjoys seamless task decomposition and substantial parameter sharing across tasks. Uni3DL has been rigorously evaluated across diverse 3D vision-language understanding tasks, including semantic segmentation, object detection, instance segmentation, visual grounding, 3D captioning, and text-3D cross-modal retrieval. It demonstrates performance on par with or surpassing state-of-the-art (SOTA) task-specific models. We hope our benchmark and Uni3DL model will serve as a solid step to ease future research in unified models in the realm of 3D vision-language understanding. Project page: https://uni3dl.github.io/ .