One particular APBT strain was crossbred to create developed a specific, stockier, physique that breeders originally misrepresented as purebred American Pit Bull Terriers. Within that span of time different strains of APBT emerged within the breed, each with different physical attributes. The APBT has maintained a characteristic appearance and temperament for over a century. The American Pit Bull Terrier (APBT) was the foundation (parent breed) used to create the American Bully. There is consensus that at least five other breeds were used to attain the more 'bully' physical traits desired as well as the more diminutive size of some lines. The American Bully, as it is now known, began development in the 1980s with the majority of the final behavioral and aesthetic product being completed in the 1990s. Temperament in adult dogs is very much dependent on training, and the breed can be very demanding and needs to be properly trained. There are several types, ranging from pocket to XXL in size and weight. The founding registry (ABKC) divided the American Bully into four categories, including the Pocket, Standard, Classic, and XL, whereas other registries, including the UKC, have approved one consistent size standard. Neither The Kennel Club nor American Kennel Club (AKC) have recognized or accepted the American Bully into their registry as a purebred dog.

In 2008, the American Bully was recognized by the European Bully Kennel Club (EBKC), and on July 15, 2013, by the United Kennel Club (UKC). Their published breed standard basically describes the dog as giving the 'impression of great strength for its size'. The American Bully is a modern breed of dog that was developed as a companion dog, and originally standardized and recognized as a breed in 2004 by the American Bully Kennel Club (ABKC).

Pocket pit