The former X Factor star will voice a character in the new animated film, which arrives in cinemas on Friday, 27 March.
Stacey's voice will appear exclusively in the UK version of the movie.
Other celebrities who will voice characters in the British edition include TV personality Alan Carr, and YouTube stars Joe Sugg and Caspar Lee.
Sponge Out Of Water movie features characters from the hit Nickelodeon show (obvs!) about SpongeBob Squarepants, everyone's favourite sea-dwelling creature.
The film has already been released in the US with stars including Antonio Banderas voicing the characters. It's already grossed more than $150 million worldwide.
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