The uniforms of the Royal Navy have evolved gradually since the first uniform regulations for officers were issued in 1748. The predominant colours of Royal Navy uniforms are navy blue and white. Since reforms in 1997 male and female ratings have worn the same ceremonial uniform.

Royal Naval uniforms have served as the template for many maritime uniforms throughout the world, especially in the British Empire and Commonwealth. The uniforms of the Royal Naval Reserve, the Royal Fleet Auxiliary, the Maritime Volunteer Service, the Sea Cadet Corps, the Navy branch of the Combined Cadet Force and the Volunteer Cadet Corps, as well as modern uniforms of Trinity House, the Royal Australian Navy, the Royal New Zealand Navy, the Royal Malaysian Navy and the Indian Navy are virtually identical to Royal Naval uniforms, with the exception of flashes at shoulder height and on rank slides. The Royal Canadian Navy on the other hand, does not wear dress uniforms similar to the Royal Navy anymore. In addition to the dress uniforms that is more similar to the U.S. Navy, the traditional sailor suit is no longer worn and some distinctly Canadian rank insignia and titles are used; e.g., master sailor.

Uniform regulations for officers were first issued by Lord Anson in 1748, and remained unchanged for nearly twenty years. Reportedly, the officers themselves advocated its adoption, as they "wished to be recognised as being in the service of the Crown." The "best uniform", consisting of an embroidered blue coat with white facings, worn unbuttoned with white breeches and stockings, was worn for ceremonial occasions; the "working rig" was a simpler, less embroidered uniform for day-to-day use. In 1767 the best uniform was abolished and replaced by the working rig, with a simpler "undress" uniform for day-to-day use. By 1795, as a result of the French Revolutionary Wars, a plain blue "undress" coat had been introduced for everyday use, and epaulettes were officially introduced. By 1846, all officers wore epaulettes. The white facings came and went over the years, briefly becoming scarlet (1830-1843). Though stripes of lace on the cuffs had been used to distinguish the different ranks of admiral since 1795, the first version of current rank insignia, consisting of stripes with a "curl" in the top one, was introduced for all officers in 1856.

In 1825, the white breeches were replaced by trousers for officers serving in the United Kingdom, although the practice of wearing white trousers with naval uniforms (popularly known as "Wei-Wei Rig") continued for officers serving overseas (e.g. in the West Indies and China) until 1939. Throughout the nineteenth century, there was great variation; officers paid for their own uniforms, and often adapted it to fit civilian fashion of the time, as the Admiralty regulations were not highly prescriptive.

For service in tropical climates, a white tunic and trousers were introduced in 1877. During World War II, a blue working dress on the lines of battledress was approved. Until 1956, caps were worn with white covers in summer months, and a thicker black cover in the winter, before the white cap became standard all year round. This was partially reversed in 2021 for Royal Navy submarine officers only who, along with submarine qualified ratings, were authorised to wear caps with a black cover rather than white, year-round.

The distinctive white collar patch of the midshipman first appeared in 1758.

Uniform for ratings was first established in 1857. Prior to this, most seamen wore "slops", or ready-made clothing sold to the ship's crew by a contractor; many captains established general standards of appearance for the seamen on their vessel, but there was little or no uniformity between ships. On one occasion in 1853, the commanding officer of HMS Harlequin paid for his boat crews to dress as harlequins, an incident which may have contributed to the Admiralty's decision to adopt a standard uniform.

A number of changes have been introduced since the introduction of the first rating uniform, notably the removal of the blue jacket in 1890, and the replacement of bell-bottoms by flared trousers in 1977.^{[clarification needed]} In 1997 there was a major standardisation programme, meaning that all ratings now wear the same ceremonial uniform for the first time in history.