Full-scale, 3D, time-dependent aerodynamics and fluid–structure interaction (FSI) simulations of a Darrieus-type vertical-axis wind turbine (VAWT) are presented. A structural model of the Windspire VAWT (Windspire energy, http://www.windspireenergy.com/) is developed, which makes use of the recently proposed rotation-free Kirchhoff–Love shell and beam/cable formulations. A moving-domain finite-element-based ALE-VMS (arbitrary Lagrangian–Eulerian-variational-multiscale) formulation is employed for the aerodynamics in combination with the sliding-interface formulation to handle the VAWT mechanical components in relative motion. The sliding-interface formulation is augmented to handle nonstationary cylindrical sliding interfaces, which are needed for the FSI modeling of VAWTs. The computational results presented show good agreement with the field-test data. Additionally, several scenarios are considered to investigate the transient VAWT response and the issues related to self-starting.