A foldable child booster seat based on the origami and popup technique. The booster seat is light and easy to be folded flat into a compact form for storage and transport. The foldable booster seat, comprising: a plurality of rigid substrates, each rigid substrate is interconnected to another by one or more integrated hinges or flexible parts allowing the rigid substrate to fold either inward or outward when folding up; wherein when the foldable booster seat is folded flat, the rigid substrates are stacked together; and wherein when the foldable booster seat is folded up, the rigid substrates are arranged to form the shape of a chair or stool.