The Magic Kingdom was the first park built at the resort, it opened on October 1, 1971. The park saw an estimated 17 million visitors in 2007, making it the most visited theme park in the world.

Designed and built by WED Enterprises (now known as Walt Disney Imagineering), the park's layout and attractions are similar to Disneyland Park in Anaheim, California.

The Walt Disney Company began construction on the Magic Kingdom and the entire Resort in 1967 after the death of Walt Disney; however, Walt was very involved in planning The Florida Project in the years prior to his death. The park itself was initially built similar to the existing Disneyland in California, however the Magic Kingdom was built in a larger area. The Magic Kingdom also improved upon Disneyland's design. According to a story, Walt Disney once saw a Frontierland cowboy walking through Tomorrowland at Disneyland and wanted to eliminate ruining the illusion like this in the new park. In order to alleviate this, the Magic Kingdom was built over a series of tunnels, called Utilidors, a portmanteau of utility and corridor. With these tunnels cast members were able to move through the park away from the guests and not ruin the illusion of the show. Because of Florida's high water table, the tunnels could not be put underground, so they were built at the existing grade. This means that the park is actually built on the second story, and it gives the Magic Kingdom an elevation of 107 feet. The area around them was filled in with dirt removed from the Seven Seas Lagoon which was being constructed at the same time. The tunnels are only under areas that were built in the initial construction and were not extended with additions to the park. The tunnels are mostly found in the Magic Kingdom because of financial constraints, but they were meant to be employed in all subsequent Walt Disney World parks. Epcot's Future World and Pleasure Island each have a smaller network of utilidors.

The Magic Kingdom opened as the first part of Walt Disney's planned Florida Project on October 1, 1971. It was the only theme park on the resort at the time and opened concurrently with two hotels on the property: Disney's Contemporary Resort and Disney's Polynesian Resort. The park opened with twenty-three attractions, three unique to the park and twenty copies of attractions at Disneyland. The Walt Disney Company promised to increase the attractions with more attractions similar to Disneyland and other unique attractions. The attractions were split into six themed lands, five copies of those at Disneyland and the unique Liberty Square which was planned for Disneyland, but never built.