Accurate tracking of a user’s body pose while wearing a virtual reality (VR), augmented reality (AR) or mixed reality (MR) headset is a prerequisite for authentic self-expression, natural social presence, and intuitive user interfaces. Existing body tracking approaches on VR/AR devices are either under-constrained, e.g., attempting to infer full body pose from only headset and controller pose, or require impractical hardware setups that place cameras far from a user’s face to improve body visibility. In this paper, we present the first controllerless egocentric body tracking solution that runs on an actual VR device using the same cameras that are used for SLAM tracking. We propose a novel egocentric tracking architecture that models the temporal history of body motion using multi-view latent features. Furthermore, we release the first large-scale real-image dataset for egocentric body tracking, EgoBody3M, with a realistic VR headset configuration and diverse subjects and motions. Benchmarks on the dataset shows that our approach outperforms other state-of-the-art methods in both accuracy and smoothness of the resulting motion. We perform ablation studies on our model choices and demonstrate the method running in realtime on a VR headset. Our dataset with more than 30 hours of recordings and 3 million frames will be made publicly available.