The flugelhorn (also spelled fluegelhorn) is a brass instrument resembling a cornet but with a wider bore. It is the soprano member of the saxhorn (also known as tuba) family developed by Adolphe Sax (who also developed the saxophone) and is built in the same Bb pitch as many trumpets and cornets. It usually has three valves and employs the same fingering system as other brass instruments. It can thus be played without too much trouble by trumpet and cornet players, though some adaptation may be needed to their playing style.

The tone is fatter and usually regarded as more "mellow" and "dark" than that of the trumpet or cornet. It has a similar level of agility to the cornet but is more difficult to control in the high register where in general it "slots" or locks on to notes less easily. It is not generally used for aggressive or bright displays as both trumpet and cornet can be, but tends more towards a softer and more reflective role. Its main areas of use are in jazz and in the brass band, though it does get occasional use in orchestral writing.

Some modern flugels are built with a fourth valve which takes them down in pitch an extra fourth, adding a useful area of low range which when coupled with the dark sound gives an interesting extension to the instrument's abilities.

A standard 3-valved Bb model