A shoe horn is a dressing aid used to help guide feet into tight-fitting dress shoes, sports shoes or boots. The shoe horn's blade is placed firmly against the back of the shoe (called the counter in footwear terminology) and the user's heel slides against the smooth surface of the horn. The shoe horn is then removed without damaging or warping the 'counter'. Some shoe horn models feature an extended handle, while others have a short blade which curves into a handle.

Back in the days when formal footwear was the norm, a shoe horn was every bit as common in the home as a hair brush or an umbrella. With advances in footwear design and a shift towards sports shoes and boots for casual use, shoe horns have become far less common. Today's shoe horn owner is more likely to use it to avoid excessive bending following surgery or other medical situation. Putting on shoes may become challenging for the elderly as well, so health catalogs often promote a shoe horn as a dressing aid in conjunction with other reach extenders.

A shoe horn may be constructed from metals such as aluminum, brass or stainless steel with an epoxy coating. Plastic is also a common shoe horn construction material, along with bone or ivory. One end of the shoe horn ends in a rounded blade curved to fit the interior of most shoes. The curved end is pressed against the back of the shoe, and the users heel slides along the concave side into the shoe. The horn end often looks like a duck's beak. There may be a sturdy handle attached to the blade which extends close to the user's knee area. The tip may be decorative, or it may be another dressing aid designed to hook clothing.

The term 'shoehorn' has fallen into popular usage as a metaphor for creating extra space through force. We might say that an emergency patient was shoehorned into the appointment book, or a last-minute addendum was shoehorned into a pending piece of legislation.