SeaWorld was founded in 1964 by Milton Shedd, Ken Norris, David Demott and George Millay. The four graduates of UCLA originally set out to build an underwater restaurant and marine life show. When the underwater restaurant concept was deemed unfeasible, they scrapped those plans and decided to build a park instead, and SeaWorld San Diego was opened on March 21, 1964. With only a few dolphins, sea lions, 6 attractions and 22 acres (89,000 m2), the park proved to be a success and more than 400,000 guests visited in the first 12 months.

The second SeaWorld location, SeaWorld Ohio, opened in 1970, followed by SeaWorld Orlando in 1973. Harcourt Brace Jovanovich, Inc. (HBJ) purchased the company in 1976 and SeaWorld San Antonio later opened in 1988. The Anheuser-Busch Company then purchased the SeaWorld parks in 1989 and put them into its Busch Entertainment division. In 2008, Anheuser-Busch was purchased by Belgian-Brazilian brewer InBev. InBev had a reputation as a cost-cutting company that was not interested in holding non-beverage businesses, and the Busch Entertainment division was later sold to the Blackstone Group in 2009. The company was renamed SeaWorld Parks & Entertainment in December 2009. In 2013, Blackstone shortened the company's name to SeaWorld Entertainment and sold 37% of it in an initial public offering. In 2024, SeaWorld Entertainment changed its name to United Parks and Resorts.