Kelly Clarkson felt like "such a jerk" after unintentionally ruining the magic of Disney film Frozen for her daughter by explaining the animated characters aren't real.

The Because of You hitmaker inadvertently broke the spell of the movie blockbuster for four-year-old River Rose as she tried to get her little girl excited for her upcoming animated release, UglyDolls, in which Kelly voices lead character Moxy.

"I actually feel kinda bad because I didn't really realise what I was doing," the singer explained. "When I showed her (the film), I was so excited to show her 'cause she loves animated films.

"I'm like, 'Look, this is mummy's voice!' I show her the trailer and she was kinda not getting it.

"I was like, 'You know like how (Frozen characters) Elsa and Anna (are voiced by actors)...' and all of a sudden I was like, 'Did I just ruin that for my daughter?' So now she knows that Elsa and Anna are like, real humans and not (just cartoons)."

Kelly could see young River's brain working as she came to the realisation, and she soon regretted her actions.

"I felt like such a jerk!" she exclaimed. "It was so defeating. Her eyes, she was like, (on the verge of tears) when she got it, and I was like, 'Oh, God!' I didn't mean to do that, but I was just excited!"

UglyDolls marks Kelly's first role as a movie lead, and she admits the storyline, about a group of pals who confront issues about fitting in as they learn to love themselves, hit pretty close to home for the 36 year old, as it reminded her of being bullied during her childhood.

"I cried (at the movie idea) - that's how they (producers) reeled me in!" she laughed on U.S. morning show Live with Kelly & Ryan. "They showed me a little sketch and I was just (crying). I was like, 'Oh my God, it's like my childhood all over again!' But it's so good, it's funny."

UglyDolls, which also stars Emma Roberts, Blake Shelton, Nick Jonas, Janelle Monae, and Pitbull, opens in theatres next month (May19).