SIGNeRF is a novel method for fast and controllable NeRF scene editing and object generation into existing scenes. It introduces a new generation update strategy that ensures 3D consistency when editing images without iterative optimization. SIGNeRF leverages the advantages of ControlNet's depth-conditional image diffusion models, allowing for editing existing NeRF scenes in a single forward pass through a few simple steps. It can generate new objects into existing NeRF scenes or edit existing objects, enabling precise control over the scene.