Abstract: The apparatus has a structure with two frames which can move towards each other and between which the mattress is locked. The frames support a plurality of devices for applying the quilting braces. Each device comprises a needle, to which a quilting brace is coupled; the needle is driven through the mattress. On the other side of the mattress there is provided a unit which applies a tuft to the quilting brace guided by the needle. During this operation, the mattress is compressed so that once it is released it expands and tensions the applied quilting braces.