PetSmart Inc. is an American retail chain operating in the United States, Canada, and Puerto Rico engaged in the sale of specialty animal products and services such as grooming and dog training, cat and dog boarding facilities, and daycare. PetSmart also offers a varied selection of animals for sale and adoption such as birds, fish, amphibians, reptiles, and several breeds of small animals like guinea pigs, chinchillas, gerbils, hamsters, and mice.

PetSmart was founded in 1986 and opened its first two stores in August 1987 under the name PetFood Warehouse in the Phoenix area. In 1989, the name and logo changed from PetFood Warehouse to PetsMart. PetsMart continued to grow and in 1993 went public on the NASDAQ stock exchange listed under the symbol "PETM". In 1994, PetSmart formed PetSmart Charities Inc., a nonprofit organization dedicated to ending euthanasia and finding homes for homeless pets. Petsmart.com made its debut in July 1995. In early 2000, PetSmart remodeled most of its stores in a plan they called "Eagle," which changed many stores from a front-half storefront/back-half warehouse feel to an all-over standard retail market. In August 2005, the company announced that it was rebranding its name from PetsMart to PetSmart. This move, which stressed "Smart" over "Mart," was designed to announce its evolution from a pet supply store to a solutions-oriented company.

As of September 2016, PetSmart operated approximately 1,477 stores and various locations with PetSmart's PetsHotels, and Doggie Day Camps. Certain locations also share space with their corporate partner, Banfield Pet Hospital.

In December 2014, PetSmart was fully acquired by BC Partners for $8.7 billion. PetSmart acquired Chewy in 2017.

PetSmart owns several brands that produce a variety of products including Grreat Choice (previously Award) which is a line of dog food as well as dog and cat hard goods. Authority is a premium dog and cat food line that PetSmart distributes and Simply Nourish is a super-premium dog and cat food line offering canned and dry food, limited ingredient, and grain-free formulas. Top Paw is a private label used for dog hard goods.

PetSmart owns several brands which produce products for felines including Authority cat food, which is considered a premium food. Additionally Grreat Choice, Simply Nourish, is comparable to top level brands such as Wellness and Blue Buffalo. Also available are lines of cat litter and litter-related products. Toy Shoppe and Whisker City which produces cat and dog toys and furniture.

PetSmart sells fish tanks, stands, and aquarium decorations and accessories under the Top Fin name. Bird and small pet products are created under the All Living Things label, and includes most items necessary for bird and small animal husbandry.

In January 2008, PetSmart temporarily suspended sales of birds in all U.S. stores as a precautionary measure after random testing found a small percentage of cockatiels that tested positive for psittacosis, a fairly common infection in birds that may produce cold-like symptoms. PetSmart resumed selling live birds again in April 2008 after comprehensive testing and treatment.

Formerly, certain PetSmart stores included a State Line Tack section. It provided a wide selection of saddles, halters, bridles, saddle pads, etc. State Line Tack also sold feed and other equipment for the care of horses.

In 2007, PetSmart put State Line Tack, including all catalog and internet business, up for sale and effectively removed all State Line Tack merchandise from stores. State Line Tack was eventually purchased by Horse.com, one of many websites owned by Pets United.

The original PetsHotel was developed and operated by David Mackstellar and Rodger Ford in Arizona. PetSmart purchased PetsHotel from Mackstellar and Ford in 2000 and presently, PetSmart continues to create and operate PetsHotels within their locations throughout the US and Canada.

PetSmart has helped stray pets find homes with families. Rather than selling dogs, cats, rabbits, and other larger animals in the store, PetSmart donates space to local rescue groups. Rescue groups are also provided with donations of food, litter, and other supplies. Fees from adoptions are collected by the groups themselves. With each adoption, PetSmart gives the new guardians a book which provides basic care information for their new pet. As of September 22, 2016, over 7,000,000 pets have been adopted through Petsmart adoption centers. Biannually, PetSmart hosts an adoption weekend featuring more adoptable pets than at any other time of the year.

PetSmart Charities, a nonprofit 501(c)(3) organization, also raises money for local adoption groups, including groups for which it does not offer in-store space. In many stores, donations are collected at the register via traditional drop boxes. Some stores also ask customers if they wish to donate a dollar at the register when they use a credit or debit card. PetSmart charities also has an annual donation drive. Proceeds from Petsmart Charities events are given to over 3,400 adoption partners. PetSmart Charities claims that of the six to eight million pets collected by rescue agencies, three to four million are euthanized simply because they do not have a loving home.

PetSmart Charities Inc. is set to award the Austin Humane Society the first of three grant installments totaling $227,000 to assist in funding AHS's new Feral Cat Spay/Neuter Program.

PetSmart Charities is also known for its Rescue Waggin' program. The program operates specially-designed trucks that transport adoptable dogs from areas that are overpopulated to partner shelters where adoptable animals are in demand. Rescue Waggin' operates trucks in the Midwest and the Northeast regions of the United States. The program has saved more than 10,000 pets since 2004.

PetSmart also operated an online Pet Parent community at Pets.com.

PetSmart has been the subject of public criticism by animal rights organization People for the Ethical Treatment of Animals for the company's sale of live birds. PETA alleges that it is cruel to sell birds bred in warehouses and feels that the breeding of the birds is similar to the use of puppy mills. PETA renewed its demands that PetSmart permanently stop selling live birds after the voluntary halt in bird sales because of the psittacosis outbreak in January 2008.

PETA also claims that the use of pest control glue traps within PetSmart stores is cruel. PETA feels that because the stores sell various species of rodents, that it is hypocritical for them to engage in rodent pest control. PetSmart counters that it is unfair to characterize its bird breeders as similar to puppy mills since these operations must meet the company's veterinarian established and industry leading standards for the breeding, care and transportation of these pets. Also, small pets sold in the stores are bred to be pets and should not be confused with wild rodents, which carry disease and are destructive to property. It maintains that essentially all major retailers, restaurants, and grocers with rodent control programs effectively use glue traps.

On January 23, 2008, PETA posted a press release accusing one of Petsmart's largest vendors, Rainbow World Exotics, of neglect and cruelty to animals. Videotape provided by an undercover PETA member who infiltrated the facility as an employee shows small animals treated cruelly and neglected. The more serious allegations included laypersons (not vets) neutering animals with unsafe provisions, live animals thrown in the trash, loose animals killed intentionally, and sick animals killed or left to die with no veterinarian interaction attempted. After these allegations PetSmart launched an investigation which reported discovering no serious wrongdoing by Rainbow, although they agreed that a neutering which was videotaped did not meet their or veterinary standards. PETA is filing complaints with the USDA and pursuing criminal charges with the county of Hamilton, Texas, where Rainbow World exotics is located.

In January 2016, PETA released details of an investigation of Holmes Farm, a major supplier of live animals to Petsmart, Petco and Pet Supplies Plus, which highlighted abusive conditions at what is described as a complex of "filthy, windowless warehouses." Small animals such as rabbits, hamsters, rats, mice and gerbils were confined to overcrowded bins and often drank from contaminated water bowls or had no water altogether. Cats, who freely roamed around the facilities, regularly jumped in and out of bins and preyed on the animals within them. PETA's investigators reported that, during their observations, injured animals never received veterinary care, but instead were piled by the dozens in "feces-smeared coolers" and then gassed to death with carbon monoxide; others were put into ziplock bags and frozen to death. Over the span of roughly three months, PETA’s investigator found hundreds of dead animals at the complex, often in habitats which contained no drinking water.

In February 2016, another PETA investigation discovered rampant abuse and neglect at Mack, an Ohio reptile mill and a supplier for Petsmart, including, among other things, frogs, lizards, turtles and other animals being "crammed into filthy, crowded plastic bins stacked into shelving units like old bank statements. Living beings deprived of water for days or even weeks. Sick and injured animals denied veterinary care. Emaciated, severely dehydrated animals desperate for water. Animals cruelly killed by being gassed or frozen to death."