Determine the width of the leather ottoman by measuring from the side floor, over the top of the ottoman and ending at the floor on the opposite side. Determine the length by measuring from the floor front, over the top and ending at the rear floor of the ottoman. Add 1 inch to both measurements and write down the numbers.
Cut a piece of fabric using the adjusted measurements.
Tear off a 3-inch piece of painter's tape and attach the short ends to make a loop. Stick the loop onto the center of the top of the ottoman to hold the fabric in place while pinning the cover edges. Place the fabric on top of the ottoman so the right side faces the ottoman and the fabric drapes evenly on all sides, and press the top into the tape to hold it in place.
Grab one corner of the fabric and pull it upward so the fabric is parallel with the ottoman top. Pin the sides to mark the seam line from the top corner to the bottom corner of that edge. Repeat this step on each corner edge to create a cover that fits the leather ottoman.
Sew along each pin line with a straight stitch. Fit the cover over the ottoman to check the fit. Make adjustments, if needed. Cut the excess fabric on each corner edge to 1/2 inch from the seam.
Fold under 1/4 inch of fabric to the back side along the bottom edge of the cover and press it with an iron to hold it. Fold under another 1/4 inch and press with an iron. Secure the hem by sewing a straight stitch close to the inside fold.