
The first show took place in May 1877, at Gilmore's Garden (later to become Madison Square Garden). That show drew over 1200 dogs and proved so popular that its originally scheduled three days became four, with the club donating proceeds from that fourth day to the ASPCA for creation of a home for stray and disabled dogs. The Westminster Kennel Club predates the formation of the American Kennel Club by seven years, and became the first club admitted to the AKC after AKC's founding in 1884. Breed parent clubs (e.g., the Afghan Hound Club of America) create the standards for judging their breeds, with the AKC administering the rules about shows and judging. Dogs are judged against their breed standards, to see how close each dog matches the standard, which is a written description of the ideal specimen of that breed. Standards may include references relating form to function in the performance of the job that the dog was bred for, and may also include items that seem somewhat arbitrary such as color, eye shape, tail carriage and more. While many breeds no longer need to perform their original jobs and are bred mostly for companionship, they should still have the innate ability and physical makeup to perform those jobs, and this is what the judge looks for.

Competition in Junior Showmanship (for handlers ages 8–18) has been held since 1934. The eight finalists all receive scholarships for post-secondary schooling. In addition, each year the club (through its Westminster Kennel Foundation) awards veterinary school scholarships for students from six schools. The show has been broadcast on live television since 1948[citation needed]. The program typically airs on a Monday and Tuesday. The Monday night broadcast is shown on CNBC and the Tuesday night broadcast on USA Network; USA itself holds the rights to the event but must defer Monday night coverage to CNBC due to its airing of WWE Raw. At the Garden, it has enjoyed sellout status since 2005, as tickets sell quickly once they go on sale each Fall. Indicative of its amazing worldwide popularity, more than 700 press credentials are issued to media attending in person from more than 20 countries. In addition, each year the Westminster Web site (www.westminsterkennelclub.org) has millions of visitors from around the world (about 12 million page views by users from more than 170 countries).
The winning dog becomes "America's Dog" for the next year. It begins its reign with a media tour on the day following the show with appearances on virtually all television network morning shows, a visit to the Observation Deck at the Empire State Building, and much more. The event is embraced in New York City every February, with salutes from such world-famous partners as the Empire State Building, which lights its tower in purple and gold (Westminster colors) during the show; Saks 5th Avenue, which features a street window with a Westminster-themed display; and the New York Stock Exchange, which invites the winner to ring the opening bell following its big win.