Paint the walls a light color. White paint can be used if you're going for a black and white theme. However, you might find a black and white room too sterile and may prefer to add in a color. Beige, cream and light gray are often used. While you may not want to paint your walls these colors, light blue, light green and light orange all work well for accent colors for a black leather sofa.
Lighten up the room with accent chairs. The chairs should coordinate with the paint color yet tie in with the black sofa. For example, if you painted the walls a beige color, you could use a beige accent chair with dark wood legs, which will coordinate with the sofa while the beige fabric ties into the wall color. Patterned accent chairs also stand out against the dark, solid color of the sofa. A glass coffee table and end tables can make the room look lighter and more open. You can also use a light color ottoman instead of a coffee table.
Select curtains and rugs that coordinate with your color palette. If you have a dark floor, you can lighten it by adding light carpet or a colorful area rug. Using a patterned rug helps break up the dark, solid color of the sofa.
Accessories are key in lightening up the room. Use light colored pillows of various fabrics and textures on the black leather sofa. Patterns work well to break up the solid color. Use lamps to provide ample light in the space, and use your color palette for the lamp base. Sleek wrought iron lamps work well with black leather. Whether you have chosen light green, beige or light blue as your accent color, it should be brought into the room via pillows, vases and artwork.