Start by cutting a rectangular patch a few inches larger than the damaged area. Ideally, use leftover wallpaper from the original installation. If none is available, source a matching piece from an inconspicuous spot, such as behind the refrigerator, inside a cabinet, or behind a mirror.
Check how the original wallpaper was hung. For pre-glued paper, moisten the back of your patch with a damp sponge to activate it. Otherwise, apply a thin, even layer of wallpaper paste to the back.
Align the patch precisely with the existing pattern (Image 1), then press it firmly into place (Image 2). Let it adhere for 3-5 minutes.
Once the paste sets, use a sharp utility knife with a fresh blade and a straightedge to score a rectangle just inside the patch edges (Image 1). Cut clean, straight lines to avoid jagged edges. Remove the surrounding excess wallpaper, then gently lift out the center patch (Image 2).
Lift the corners of the underlying damaged piece with the knife and carefully peel it away, preserving the cutout shape.
Realign the prepared patch to match the pattern and cutout perfectly, then press it firmly into place. Smooth thoroughly with a wallpaper sponge for a seamless finish.
