Labialisation is a secondary articulatory feature of sounds in some languages. Labialised sounds involve the lips while the remainder of the oral cavity produces another sound. The term is normally restricted to consonants. When vowels involve the lips, they are called rounded.

The most common labialised consonants are labialised velars. Most other labialised sounds also have simultaneous velarisation, and the process may then be more precisely called labio-velarisation.

Labialisation may also refer to a type of assimilation process.