Fe based amorphous alloys with high boron and gadolinium contents have been developed through a systematic alloy design technique for neutron shielding applications. Amorphous ribbons with the Gd content up to 10at.% were prepared by a melt-spinning method and used as reinforcements within polyester matrix and concrete matrix, respectively. Excellent neutron shielding efficiency about 75% was obtained from the polyester hexahedron composites (5cm×5cm×1cm) including only 1vol% ribbon with the composition of Fe72B15Mo3Gd10. Moreover, a concrete composite (φ 10cm×5cm thick) in which the amorphous ribbons with the composition of Fe72B24.5Mo3Gd0.5 were uniformly distributed exhibited neutron shielding efficiency of around 86% demonstrating the applicability of amorphous ribbons as reinforcements in various composites for neutron shielding facility constructions.