A footstool is a piece of furniture, the purpose of which is to provide comfort to a person seated in, for example, a chair or sofa. It is typically a short, wide, four-legged stool with a padded fabric top. It allows the seated person to rest their feet upon it, thus supporting their legs at a mostly horizontal level.

A shorter form of footstool may be used for support when a person's (usually a child's) feet do not reach the floor while seated. In this case, the person's lower legs are not outstretched horizontally; the footstool is simply placed under the feet. A piano footstool used in conjunction with a piano bench does just this.

There appears to be no distinction between the two forms in terms of naming. The main distinction in terms of function is that in the first form, the lower legs are usually held straight (perhaps one crossed over the other) while in the second form, the knees are bent as is expected.

Generally, any object of suitable elevation may be employed as a makeshift footstool. Another seat, a desk, or a table may serve. These options are usually considered inconsiderate since feet, and especially shoes (by their nature) tend to collect more dirt than a person's working area or pants.

The term footstool may also be applied to shorter stepladders , but this usage is less common. A heavily upholstered footstool of the first described form is called an ottoman.