Which Nintendo Switch game was the first Kirby title with fully 3D platforming?

Kirby and the Forgotten Land was the first Kirby title with fully 3D platforming.

HAL Laboratory developed the game for Nintendo Switch, and Nintendo released it worldwide on March 25, 2022. Earlier main Kirby platformers generally used side-scrolling 2D stages, even when they included depth effects or three-dimensional presentation.

The adventure takes Kirby to the Forgotten Land, a mysterious world featuring abandoned human-made environments. Kirby must rescue the Waddle Dees after they are captured by the Beast Pack, while new abilities and the Mouthful Mode expand his familiar repertoire.

The game is not the first Kirby release to use 3D graphics or three-dimensional arenas. Its distinction is that it makes free movement through fully 3D platforming stages the central structure of a mainline Kirby adventure.