British overseas territory flag consisting of a dark blue field (background) with a Union Jack (United Kingdom, flag of the) in the upper hoist quarter and a badge containing the Cayman Islands coat of arms (arms, coat of) in the centre of the fly end; the flag may be described as a defaced British Blue Ensign. The flag's width-to-length ratio is 1 to 2.

The Cayman Islands, a British possession since the 1670s, were a dependency of Jamaica until July 1959, when they became a separate colony; they later became a British overseas territory. The Union Jack serves as the state flag and, with the badge of the islands in the centre, as the standard of the governor. The badge displays the coat of arms granted on May 14, 1958. Those arms were placed on a white disk on the Blue Ensign, and this was used as the colony's surrogate national flag and its ensign for government vessels. In 1999 the badge, as used on the ensign, was enlarged and outlined in white instead of appearing on a white disk. In addition, the British Red Ensign with badge affixed was for years flown unauthorized on private vessels and as the Cayman courtesy flag. The usage of both ensigns was legalized in 1988.

The coat of arms consists of a red shield bearing a yellow lion at the top and blue and white wavy stripes at the bottom, on which are affixed three yellow-bordered green stars. Above the shield is a crest consisting of a white and blue torse (twisted band) surmounted by a yellow pineapple behind a green turtle. Beneath the shield is a yellow ribbon bearing the motto “He hath founded it upon the seas.” The lion represents England, and the stars are for the islands of Grand Cayman, Little Cayman, and Cayman Brac. The blue and white stripes suggest the Caribbean Sea. The turtle is for the islands' original Spanish name (Las Tortugas; “The Turtles”) and for the numerous turtles still living there. The pineapple recalls the islands' connection with Jamaica, which has five pineapples in its coat of arms. The motto is from Psalms 24:2.