A bicycle bell is a percussive signaling instrument mounted on a bicycle for warning pedestrians and other cyclists. They are usually mounted on the handlebars and thumb activated.

The bicycle bell was invented by John Richard Dedicoat, and patents for bicycle bells appear as early as 1877.

The most common bells are actuated by a thumb-operated lever that is geared to rapidly rotate two loosely slung metal discs inside the bell housing. Said discs repeatedly rattle and strike the bell to produce a sound not unlike that of an electric bell. This type of bell comes in left and right handed versions. Left handed versions are mounted on the left side of the handle bars and are used in countries that drive on the left hand side of the road. The right hand is then free to give traffic signals.

Simpler types also exist, with a spring-mounted external clapper that creates a "ding-ding" sound when the clapper is pulled with a finger and released. Some bells, particularly these "ping" types, work poorly in rainy conditions because water drops clinging to the bell damp the vibrations which produce sound.^{[citation needed]}

The bell is a required piece of equipment in some jurisdictions.

In the United Kingdom, bells on new bikes were compulsory until 1983, and again since 1 May 2011.

In New Jersey, a bicycle must be equipped with a bell or other audible device that can be heard at least 100 feet away, but not a siren or whistle.

In Ontario, a bike must have a bell or horn in good working order.