Measure the dimensions of the rug with a tape measure to determine how large the nonslip underlayment must be.
Purchase an underlayment with a rubber underside that is about 1 to 2 inches less in width and height than the rug. The layer may have an adhesive surface on top that will stick to the underside of the rug, or it may have a woven surface made of natural fibers that will stick to the underside of the rug with its rough texture.
Set the underlayment on the tile floor where you want to place the rug. Make sure the rubber side of the underlayment touches the tile.
Remove any adhesive backing on the top of the underlayment, if applicable, to enable you to adhere the underlayment to the rug.
Place the rug over the underlayment, centering the rug carefully over the top. The underlayment beneath the rug should stop the rug from moving over the tile floor because of the rubber layer against the tile.