High-visibility clothing, sometimes shortened to hi vis or hi viz, is any clothing worn that is highly luminescent in its natural matt property or a color that is easily discernible from any background. It is most commonly worn on the torso and arm area of the body. Health and safety regulations often require the use of high visibility clothing as it is a form of personal protective equipment. Many colors of high visibility vests are available, with yellow and orange being the most common examples. Colors other than yellow or orange may not provide adequate luminescence for conformity to standards such as ISO 20471.

As a form of personal protective equipment, high-visibility clothing is worn to increase a person's visibility and therefore prevent accidents caused by persons not being seen. As a result, it is often worn in occupations where hazardous situations are created by moving vehicles or low lighting conditions. These occupations include railway and road workers, airport workers and emergency services. Cyclists and motorcyclists may also use high-visibility clothing to increase their visibility when operating amongst motor traffic. Hunters may be required to wear designated high-visibility clothing to prevent accidental shooting.

Some reflective tapes used on high-visibility clothing can reflect as much as 82% of the source light, causing retinal damage. It is therefore recommended that aircraft pilots, professional truck/bus drivers, and operators of heavy machinery refrain from wearing highly reflective clothing while conducting their duties.