According to reports on Reddit and Nintendo Life, Wii Karaoke U does not censor explicit and mature lyrics like Sony's SingSong or Rock Band's Harmonix, nor does the game present users with the mature content warning before each explicit song. The only warning available is on the loading screen, which warns user that none of the songs included in the game have been rated by PEGI.

The explicit lyrics are also included in the free demo version of Wii Karaoke U  which permits one hour of play before it prompts players to purchase the game, and any inappropriate lyrics contained therein, is open to download for all users.