The objective of this paper is to investigate laminar-to-turbulent transition-induced vibration of a NACA66 hydrofoil section at 4°angle of attack and Re=450,000. Direct Numerical Simulation (DNS) is used to simulate the three-dimensional incompressible flow, and is coupled with an equation of motion for a rigid hydrofoil supported at the elastic axis by a torsional spring and damper. The coupled 1-DOF DNS is carried out on a massively parallelised open source code Nek5000, which is a spectral element code, to solve the incompressible Navier–Stokes equations. The results show that the pressure gradient of the hydrofoil can be strongly affected by vibrations of the foil, thus changing the location of transition and boundary layer characteristics, which are proportional to the amplitude of vibration and frequency ratio of the foil. Moreover, the TS waves that appear in the transition region are receptive to the natural/vibrating frequency of the foil and an early occurrence of TS waves is observed when the shedding frequency is close to the natural frequency of the system. In this case, the pitch angle and torque interact with each other and an additional multi-scaled frequency response is observed in the pitch velocity, potentially due to the interaction with the transition region.