Pile foundations are generally made to withstand enormous compressive, uplift, and lateral loads. Cylindrical or straight-sided piles are frequently used in practice. The latest developments in tensile load resistance for transmission towers, wind turbines, offshore structures, solar panels, television towers, etc. are enlarged base piles. Therefore, the current work focuses on examining the axial and oblique pullout behavior of step-tapered and belled step-tapered piles in loose sand with geogrid reinforcement. In this experimental investigation, a model box of size 1.2 m × 0.75 m × 1.5 m is used to investigate the axial and oblique pullout behavior of an aluminum model pile under various load inclination angles of 30° and 45°. By referring to literatures, the ideal size of the geogrid of 5D (where D is the base diameter of the pile) was chosen for this investigation. In comparison to cylindrical piles, the step-tapered and belled step-tapered piles show a considerable improvement in the axial and oblique pullout capacity. In the case of a cylindrical and step-tapered pile, the pullout capacity increases with an increase in the load inclination angle from 0° to 45°, whereas in the case of the belled step-tapered pile, the pullout capacity decreased with an increase in the load inclination angle. A non-dimensional parameter called the ULIR was evaluated, and the results revealed that the efficiency of the geogrid reinforcement was found to be minimal in the case of the belled step-tapered pile, but considerable improvement is observed in the case of the conventional belled pile.