A marine current turbine (MCT) that extracts energy from ocean currents should be hydrodynamically and structurally stable to generate uninterrupted power. This can be achieved through the shape optimization of MCT blades. In this work, a horizontal axis MCT of 0.8 m diameter was optimized through multi-fdelity numerical approach. The design parameters such as blade pitch angle (θ) and the number of rotor blades (NR) were modifed to increase the power coefcient (CP) and to reduce the von-Mises stress (σv) using multi-objective optimization technique. A coupled fuid–structure interaction method is used for fuid and structural analysis of MCT. Also, an analysis for identifying the cavitation inception is incorporated. A surrogate-based optimization code was used to produce a Pareto optimal front. The MCT with CP=0.451 encountered σv=125.83 MPa and a high total deformation (TD)=20.259 mm near the blade tip. The TD of the same MCT blade was later reduced to 1/3rd of its actual value by identifying an alternate turbine material. The losses due to vortices, wake generation, and cavitation study are discussed in the present work.