'azoprotein' originates from Modern English as a compound of the prefix 'azo-' (from French 'azote', ultimately from Greek 'azōtos', where 'azōtos' meant 'lifeless' and was used to name nitrogen) and 'protein' (from Neo-Latin/Greek 'proteios', where 'proteios' meant 'primary' or 'of first importance').

'azoprotein' developed from the hyphenated formation 'azo-protein' used in 19th–20th century chemical literature to denote proteins coupled with azo compounds, and eventually became written as the single word 'azoprotein' in modern usage.

Initially it referred specifically to proteins chemically combined with azo groups or azo dyes; over time the term has retained this technical meaning and is used mainly in biochemical and histochemical contexts.