In this study, three-dimensional liquid-metal magnetohydrodynamic flows in a rectangular hairpin duct with parallel inflow and outflow channels, placed under uniform magnetic fields, are analyzed based on a computational fluid dynamics method. Detailed information on flow velocity, pressure, current, and electric potential in magnetohydrodynamic duct flows is predicted. In the side layers of the inflow and outflow channels, higher velocities are observed, and M-shaped velocity profiles are presented. In the turning segment, the velocity distribution is very complex, yielding complicated induced current therein. The electromagnetic characteristics of the complicated liquid-metal flows are examined in terms of the electromotive and electric-field components of the current. The pressure almost linearly decreases along the main flow direction, except for in the turning segment. Cases with different Hartmann numbers are examined, and the larger the Hartmann number is, the larger the pressure drop is. However, the nondimensional pressure gradient is smaller in cases of larger Hartmann numbers.