Animal Crossing: Happy Home Designer is a 2015 sandbox video game developed and published by Nintendo for the Nintendo 3DS. The game was released in Japan in July 2015, in North America in September 2015, and in Europe and Australia in October 2015. The game is a spin-off of the Animal Crossing series where the player designs homes for various anthropomorphic animal characters.

Happy Home Designer received mixed reviews from critics upon release; critics praised the creative freedom and improved design controls, but criticised the lack of challenge and unrewarding gameplay loop. Many also felt the game should have been downloadable content (DLC) for Animal Crossing: New Leaf instead of a standalone release. The game sold 3.04 million copies worldwide as of March 2016 and a sequel, Happy Home Paradise, was released as DLC for Animal Crossing: New Horizons on November 5, 2021.

Animal Crossing: Happy Home Designer downplays the wider community simulation mechanics of the main Animal Crossing series in favor of focusing on house designing; players work as an employee of Nook's Homes, designing homes for other animal villagers based around their suggestions. As players progress, they will unlock additional furniture elements they can incorporate into their designs. Players can also visit the homes they have created.

The game interacts with New Leaf, primarily by allowing the player to unlock exclusive furniture through the Nookling Junction kiosk.

The game integrates with Animal Crossing Amiibo cards; scanning cards allows their respective character to visit a home that a player had designed, and allows players to design homes for other major characters such as K.K. Slider and Tom Nook.

Animal Crossing series producer Aya Kyogoku explained that Happy Home Designer was inspired by the internal process of designing homes for the animal villagers in the main Animal Crossing games, stating that "We had to think about, what kind of things would this animal like? What kind of life do they lead? Trying to figure out what they'd want was very fun, and we tried to think of a way we could get this kind of experience to players as well." Players are not tied to a specific budget when designing homes; while the concept was considered, the development team believed that such a limit placed too much of a burden on the player's creativity.

amiibo were also an influence on Happy Home Designer and a sister game, Animal Crossing: Amiibo Festival, as the development team thought that Animal Crossing amiibo would be "cute", and brainstormed new gameplay concepts for the franchise that incorporated them. The two games also have integration with each other; houses designed in Happy Home Designer can appear in-game within amiibo Festival. Eight series character amiibo were planned for release with amiibo Festival. Upon their announcement, some expressed concerns with the series moving in a different gameplay direction; however Kyogoku noted that it and amiibo Festival were spin-offs, and don't necessarily represent where the mainline series would go in the future.

On October 15, 2021, during an Animal Crossing Nintendo direct, it was announced that paid DLC for Animal Crossing: New Horizons, called Happy Home Paradise, would be released on November 5, 2021. Happy Home Paradise takes heavy inspiration from Happy Home Designer (acting as a sequel of sorts) and follows the player making vacation homes for several villagers, as well as establishments such as a school and restaurant. Lottie returns and two new characters are introduced. The player can use wallpaper on an individual wall as opposed to only all four, have villagers live with each other, among many other new features.