The zoo’s construction began in 1907, and its doors opened on December 13, 1909. During its first 40 years, the zoo expanded slowly, adding exhibits such as the Bear Grotto in 1912. In the 1940s, it gained traction by adding a monkey island and a children’s zoo. The sea lion pool, African Veldt, giraffe house, and flamingos were all added in the 1950s; in the 1960s, the zoo added an otter pool, an elephant home, and the Great Ape House. In the early 1970s, a dairy barn, the Great Catwalk, and gibbon islets were added. Approximately twenty years later (in 1991), the zoo expanded to its current size of 202 acres (82 hectares), with the addition of Australia.

The Sprint IMAX Theater, the zoo’s first IMAX theater, was built. In 1998, the enhancements resulted in a record attendance of 700,000 zoo visitors and 400,000 IMAX visitors. The zoo has expanded from a modest facility on 60 acres (24 hectares) to a 202-acre (82 ha) zoo with approximately 1,300 animals. The Orangutan Primadome opened in 2002 as part of the zoo’s transition from a city-run institution to a public-private collaboration with Friends of the Zoo (FOTZ for short).

A 20-year plan for the zoo’s future, including major upgrades, is in the works. The Discovery Barn, as well as a shortcut to Africa, opened in 2006. KidZone received an endangered species status in 2007. On September 4, 2007, the Zoo shuttered the Sprint IMAX Theater. In May 2008, the zoo’s new admission gates opened, along with new parking and animals.

The Kansas City Zoo was chosen as a breeding site for African elephants and baboons in 2006.

The zoo underwent extensive improvements in late 2005. The Discovery Barn, originally known as the Red Barn, debuted in 2006. It has a lot of exhibitions and slides for kids. Outside, there is a Peek-a-Boo Tree where children can play and receive a sky-high perspective at the top, and it, like the Discovery Barn, has a slide.

The Promenade, a wide path leading to the African elephant exhibit, was also created in 2006, allowing people to get to Africa much faster. In May 2008, the new entrance admission gates opened, along with an educational center and exhibits of North American river otters and trumpeter swans. The Tropics House opened in early 2009 behind the Sea Lion pavilion in the 1909 Building, and the polar bear exhibit premiered in August 2010 at the doorway, which was formerly occupied by stroller rental. The Helzberg Penguin Plaza debuted in October 2013, thanks to an ongoing series of fundraising events and a 1/8th cent sales tax collected from the two-county Zoological District.