This paper proposes a magnetic hemispherical wheeled robot that can adapt to pipes with different curvatures (external or internal). The hemispherical wheel, combined with an independently movable magnet holder, enhances the robot’s adhesion force on pipes with varying curvature radii. Two magnet holders suitable for the hemispherical wheel were designed. Parametric simulations were conducted to analyze the magnetic induction intensity and magnetic force magnitude of the two magnet holders at different magnet holder angles. Adhesion force experimental results indicate that under the same conditions, the cross-shaped magnet holder exhibits more stable magnetic force. Computational analysis explored the relationship between the pitch angle of the arm and the robot’s climbing at different diameters and at various inclined angles. Finally, a prototype was built for pipe climbing experiments, and the results demonstrate that the robot can move in different directions on pipes with varying diameters. In the future, we will explore different wheel materials or use injection molding processes to enhance the friction force of the wheels.