Abstract Artificial Intelligence (AI) chatbots, such as ChatGPT, have been shown to mimic individual human behaviour in a wide range of psychological and economic tasks. Do groups of AI chatbots also mimic collective behaviour? If so, artificial societies of AI chatbots may aid social scientific research by simulating human collectives. To investigate this theoretical possibility, we focus on whether AI chatbots natively mimic one commonly observed collective behaviour: homophily , people's tendency to form communities with similar others. In a large simulated online society of AI chatbots powered by large language models ( N = 33,299), we find that communities form over time around bots using a common language. In addition, among chatbots that predominantly use English ( N = 17,746), communities emerge around bots that post similar content. These initial empirical findings suggest that AI chatbots mimic homophily, a key aspect of human collective behaviour. Thus, in addition to simulating individual human behaviour, AI‐powered artificial societies may advance social science research by allowing researchers to simulate nuanced aspects of collective behaviour.