One aspect of the present invention provides a fastening strap assembly for used in a foam article. The fastening strap assembly includes a substrate having two sidewalls each formed along one side thereof in a longitudinal direction and spaced apart from each other; a substantially fishbone-shaped fastening member disposed between the sidewalls and adhered to the substrate, the fastening member having an elongate central rib and a plurality of fastening parts laterally extending from either sides of the rib and longitudinally spaced apart from each other, each fastening part having a plurality of hooks formed on a upper surface thereof; and a magnetic layer disposed between the substrate and the fastening member. The fastening strap assembly of the present invention has a unique sideway bending/curving function. Another aspect of the present invention provides a foam article, such as a seat cushion, including the sideway-bendable fastening strap assembly.