KATY Perry dressed up as Ursula from Disney classic film The Little Mermaid on last night’s American Idol.

The 34-year-old judge looked incredible as she embodied the film character and went all out with her intricate costume.

Katy really got into the show’s Disney theme, posing for photos as she rocked light purple face paint and a sheer purple top to resemble the skin of the legendary evil sea witch.

The singer chose to go all out with her eccentric makeup, as she donned a bright red lip and blue eye shadow, as well as replacing her usually neat cut into a messy grey dishevelled style like the character is seen with in the 1989 hit film.

And she really got into character with her intricate outfit design of a purple and black tentacle dress, which she was seen wearing throughout, along with the necklace which the evil witch stole from Ariel in the film, to keep her voice locked away.

However, despite her all out effort for the show, her fellow judges Lionel Richie and Luke Bryan opted not to join her in wearing costumes.

Instead, Lionel went for all black in a biker jacket and jeans, while Luke wore a beige jacket and jeans.

Katy’s look for filming seems a million miles away from her new long blonde, wavy hairdo that she debuted on Instagram on Saturday.

She captioned with the Spanish for “What’s your name?”

Fans were left stunned by the transformation, with many of them immediately commenting on the post.

One exclaimed: “OMG!!!🔥🔥🔥 I needed a warning about this for my soul.”

Another gasped: “Shes stunning with the long blonde hair.. like stunning.. like model.. like why why hasnt she done this before?”

A third disbelieving fan wrote: “Is this really Katy Perry?!? Shhook.”

Another insisted: “Way better this look than the short hair, in both look beautiful but in this you totally rock it!.”