Robotic Canvas combines swarm robotics, human-robot interaction, and art. The project creates a robotic canvas using a swarm of decentralised robots that a human can interact with to paint. Beauty emerges from the robots interacting with one another, their environment, and a human performer. Robotic Canvas is a dynamic and interactive visual art medium, capable of displaying static images or video feeds, upon which humans can paint with their physical gestures or dedicated robots. Art making therefore becomes a collaborative and immersive performance between artists, digital content, and robotic agents. Results are demonstrated through a 200-robot performance, with each robot acting as a single pixel of the canvas. We further describe and characterise the various interaction modes, called “Painting Modes”, of the system. Results from this work form the basis for future research in expressive human-swarm interactions.