The Legoland California Resort currently encompasses:

The resort site includes two hotels:

Lego opened the first Legoland theme park in Billund, Denmark in 1968, followed by a second park in Windsor, England in 1996. The Carlsbad park was the third to open, in March 1999. At the time, Lego was considering an additional United States Legoland to be located somewhere on the east coast. When the park opened, there were eight themed areas. Starting at the entrance (at the central southern part of the park) and proceeding clockwise, they were:

By 2002, Village Green and The Ridge had been combined into an area called Explore Village and the Aquazone and LEGO Technic Test Track rides had been installed at Imagination Zone. The fourth Legoland, built in Germany, opened in 2002. Dino Island and Coastersaurus opened in April 2004; the park also added Fun Town Fire Academy, a Florida-themed Miniland area, and the Block of Fame for its fifth anniversary.

Legoland California installed the first KUKA RoboCoaster in the United States in 2005. However, the weak retail toy market led to the sale of the four Legoland theme parks in July 2005 for $456 million to Blackstone Capital Partners, a private equity firm based in the United States. Blackstone had previously purchased Merlin in May 2005, which owned the Sea Life Centres and London Dungeon; the two assets were combined as Merlin Entertainments, with Lego taking a 30% ownership share in the combined Merlin Entertainments. Collectively, the four theme parks had approximately 5 million visitors per year at the time.

Under Merlin, Legoland California would add Pirate Shores (2006), a Las Vegas-themed Miniland area (2007), the Egyptian explorer-themed Land of Adventure (2008), and the 5.5-acre (2.2 ha) Legoland Water Park (2010). In 2009, Merlin requested permission to develop an onsite Lego-themed hotel in the existing parking lot; permission was granted in October and plans for the 250-room hotel were announced in 2011, making the site a resort in 2013. The first fictional Miniland area, themed with scenes from the six (at the time) Star Wars movies and the Clone Wars television series, opened in March 2011. The water park was expanded in 2014 with a Chima-themed area. A second 250-room hotel with a castle theme was added in 2018.

Attendance at Legoland California reached 2.5 million visitors in 2013 and nearly 3 million by 2015, nearly double the attendance of Legoland Florida. More than $20 million was spent per year on sales tax on food and merchandise. The park employed more than 2200 workers in total: 600 full-time, nearly 500 part-time, and more than 1100 seasonal.

In mid-March 2020, in line with other Legoland parks, the park was indefinitely shut down because of the COVID-19 pandemic and reopened on April 1, 2021.