Legoland Deutschland was opened by the LEGO Group on May 17, 2002, in Günzburg, Germany, nine months earlier than planned. During the initial operating year, the park welcomed 1.35 million visitors. In 2005 the four Legoland parks were sold to Merlin Entertainments in a 375 million Euro deal. Although generally credited as the fourth Legoland park to open and the first in Germany, an earlier theme park (now Hansa-Park) in Sierksdorf used the Legoland branding under licence from the Lego Group from 1973 to 1976.

All of the lighting for the park was done by Gallegos Lighting Design which had done the lighting for Legoland California Resort and the sound and video production for the park was done by Edward Technologies Inc. The park features Lego explore centers, roller coasters, water attractions and shows. When it opened in 2002, it contained 40 attractions, 7 themed lands and was made out of 50 million Lego bricks. 10 years later, the park expanded to eight “adventure worlds” with 50 attractions and 55 million Lego bricks. Legoland Deutschland is home to the world's largest Lego building, representing Munich's Allianz Arena and weighing 1.5 tons with dimensions of 5 meters in width and 1 meter in height. Legoland Deutschland also contains many other world records such as the largest Lego flower bed (2007), largest amount of energy generated through cycling underwater (2010), highest Lego tower (2010), largest Lego mosaic (2011), longest Lego millipede (2002), and the largest Lego brick (2005).

The park celebrated its ten-year anniversary in 2012: in that occasion, the attraction Flying Ninjago debuted, and six scenes in Miniland based on the Lego Ninjago toy series were added.

On April 22, 2013, Merlin Entertainments Group introduced an app entitled “LEGOLAND Deutschland” available for Android and Apple devices. The app features an interactive park map, ticket purchasing, a “Find my car” feature, and a day planner that has all of the day's events listed for visitors. Legoland Deutschland also introduced the electronic “express pass” which allows guests to purchase either a Standard, Premium or Gold express pass, allowing guests reserve a spot in the queue line for select attractions. In 2013, the CEO of the park, Aksel Pedersen, announced the largest expansion in the history of Legoland Deutschland and consisted of 86,000 Lego bricks. The park expanded by building the “Kingdom of the Pharaohs” themed land within Adventure Land which added the ride "Temple X-pedition". Additionally in 2013, the park expanded the Star Wars Miniland Model Display when they added a Yoda Lego model display. In 2014, Legoland Deutschland introduced the 5 million Lego block X-Wing Model Display which used to be in the theme park in the Hero Factory attraction hall for a limited time. Also Legoland introduced the new Königsburg hotel with 68 rooms. On March 28, 2015, Martin Kring, the then new general manager of Legoland, introduced the LEGO City Polizeistation, a walkthrough maze with special effects. The attraction was built into an existing building in the Imagination themed area. In 2016 High Five in Miniland and the new Drachenburg at Holiday Village were opened. In 2017 Ninjago World was opened based on the Lego Ninjago theme. The area includes LEGO Ninjago: The Ride and Lloyd’s Spinjitzu Spinner (opened in 2020). The new area ist the biggest investment since the opening in 2002. The following year, Legoland opened its next hotel. The Pirateninsel Hotel (Pirate Island Hotel) is based on a pirate theme and costed 26,6 million Euros. The building offers place for up to 594 guests.

On May 10, 2019, Manuela Stone, the former F&B director, took over the position as general manager from Martin Kring. In 2020, because of the COVID-19 pandemic, the park opened late on May 30 with only half of the normal capacity. On August 11, 2022, two roller coasters at the theme park collided with one another, causing more than thirty injuries.

On June 30, 2023, it was announced that a second park would open in the resort in 2024, based on the animated television series Peppa Pig called Peppa Pig Park Günzburg. It will be located next to the Legoland Deutschland theme park and is the second Legoland resort to receive a non-Lego attraction and Peppa Pig theme park after Florida. The park opened on May 19, 2024.