Full dress uniform, also known as a ceremonial dress uniform or parade dress uniform, is among the most formal type of uniform used by military, police, fire and other public uniformed services for official parades, ceremonies, and receptions, including private ones such as marriages and funerals. Full dress uniforms typically include full-size orders and medals insignia. Styles tend to originate from 19th-century uniforms, although the 20th century saw the adoption of mess dress-styled full-dress uniforms. Designs may depend on regiment or service branch (e.g. army, navy, air force, marines). In Western dress codes, full dress uniform is a permitted supplementary alternative equivalent to the civilian white tie for evening wear or morning dress for day wear – sometimes collectively called full dress – although military uniforms are the same for day and evening wear. As such, full dress uniform is the most formal uniform, followed by the mess dress uniform.

Although full dress uniforms are often brightly coloured and ornamented with gold epaulettes, braids, lanyards, lampasses, etc., many originated in the 18th and early 19th centuries as normal styles of military dress that, with the adoption of more practical uniforms, were eventually relegated to ceremonial functions. Before World War I, most armed forces of the world retained uniforms of this type that were usually more colourful and elaborate than the ordinary duty (known as undress), or the active service dress uniform.

While full dress uniform is predominantly worn at occasions by commissioned officers and senior non-commissioned officers, it may also be worn as optional wear at personal expense by enlisted personnel on occasions such as weddings. It is also sometimes worn by members of royal courts, orders of chivalry or certain civilian uniformed services, although some of the latter may resemble court uniforms.

The phrase "full dress uniform" is often applied in order to distinguish from semi-formal mess dress uniforms, as well as informal service dress uniforms.

Yet, a full dress uniform is sometimes simply called a dress uniform. Although many services use the term dress generically for uniforms, allowing it to refer to more modern service dress ("combat") uniforms with suitable modifiers (e.g. the British Army's obsolete Battle Dress; and the U.S. Army's obsolete Battle Dress Uniform). Therefore, the term dress uniform without prefix typically refers to full dress uniform as described in this article.

During the 19th century a division developed in most armies between the uniform worn for parade and ceremony ("full dress"), active service ("field dress") and daily working ("barrack" or "fatigue" dress). For off-duty wear outside barracks, full dress was usually worn in a slightly modified form ("walking out dress").

The British and United States armies were dependent upon voluntary recruiting and found that a smart uniform served to attract recruits and improve morale amongst those already serving. The British regimental system fostered numerous distinctions amongst different units.

However, this was not limited to volunteer armies, with conscript armies of continental Europe retaining many of the colourful features that had evolved during the nineteenth century, for reasons of national and unit pride. Thus, in 1913 most French soldiers wore red trousers and kepis as part of their full dress, the majority of British foot regiments retained the scarlet tunics for parade and off duty ("walking out"), the German Army was characterised by Prussian blue, the Russian by dark green, and the Austro-Hungary Army by a wide range of differing facing colours dating back to the 18th century.