Disclosed are a foldable support, a foldable chair, and a foldable table. The foldable support includes a foldable triangular frame, and the triangular frame includes a first connecting block, a second connecting block, a third connecting block, a first connecting rod, a second connecting rod, and a third connecting rod. The second connecting block and the third connecting block are symmetrically arranged on one side of the first connecting block, the third connecting rod is provided with a first end and a second end, the first end of the third connecting rod is rotatably connected to the second connecting block, the second end of the third connecting rod is provided with a limiting elastic column and an unlocking button, and the third connecting block is provided with a connecting groove and a locking hole. The unlocking button is in linked connection with the limiting elastic column.