Good-Feel being the development company behind Princess Peach: Showtime! was not officially revealed until the day before the game's release, where it was discovered via the game's credits. It was also revealed through the credits that the game had been directed by Good-Feel president Etsunobu Ebisu, who had not directed a game since Mystical Ninja Starring Goemon in 1997. Two weeks prior to this, however, Good-Feel's involvement was leaked via the code from the game's demo version. When asked who the development company was, Nintendo merely stated that it would be revealed in the game's credits.

Prior to the game's release, Nintendo made some minor adjustments to the game's key art, changing the eyebrows on Peach's face design slightly to appear more competitive (with some comparing it to her design in The Super Mario Bros. Movie), and changing Kung Fu Peach's expression to one of anger. Unlike similar changes made to artwork of other Nintendo games - most infamously the Kirby franchise - where an angry version would be made for Western territories and a happy version would be made for US territories, this change was made to both the Japanese and American versions of the art.

Similar to Super Mario Bros. 3, Princess Peach: Showtime! was conceived as a stage play. Unlike Super Mario Bros. 3, however, this idea was revealed early on, whereas with Super Mario Bros. 3 it was simply a fan theory until 2015 when Shigeru Miyamoto confirmed it was intentional.