Justin Guarini was Idol’s runner-up. Then he became Lil’ Sweet

He chose Idol while a Lion King offer waited

Guarini’s stage training began well before television. He joined the Atlanta Boy Choir at four and later studied vocal performance and theater at Philadelphia’s University of the Arts. In 2002, an offer to join The Lion King arrived as he prepared for American Idol’s Hollywood round; he chose Idol. Simon Cowell praised his voice at an early audition. His first-season performances included “Ribbon in the Sky” in Group 2 and “For Once in My Life” in the Top 10. For the September 3 finale, he sang “Before Your Love,” “Get Here” and “A Moment Like This.” He finished as runner-up, with Kelly Clarkson winning the season.

He learned about his label setback through a television joke

His self-titled album arrived in June 2003, the same month as From Justin to Kelly, the film he made with Clarkson. RCA dropped him that December. Speaking to TheaterMania in October 2026, Guarini recalled finding out through a Tina Fey joke on Saturday Night Live’s Weekend Update. He said the experience became part of his identity and affected his work: “It colored everything I did.” He kept recording, independently releasing Stranger Things Have Happened in December 2005 through his company, Justice Entertainment. The second album gave him a set of jazz standards to sing.

His Broadway debut began with an unaccompanied audition

In 2010, Guarini made his Broadway debut as Carlos in Women on the Verge of a Nervous Breakdown at the Belasco Theatre. His audition had required a quick decision: asked for additional material, he sang a song in Spanish without accompaniment. He joined shortly before rehearsals began and played the son of characters performed by Patti LuPone and Brian Stokes Mitchell. Guarini told TheaterMania that the costume, wig and glasses helped him enter the character. More Broadway parts followed: Will in American Idiot in 2011, Paris in Romeo and Juliet in 2013 and Fiyero in Wicked in 2014.

He slid into his Lil’ Sweet audition on his knees

The commercial audition came after his Wicked run. Guarini told Alan Seales that he felt worn out and wanted a break; his team persuaded him to attend. The character description named 1980s rock singers, and he decided to have fun with the material. He slid into camera view on his knees and improvised the sung lines. A callback followed, then a request to fly to Los Angeles. By March 2015, he appeared as Lil’ Sweet in Diet Dr Pepper commercials. He told Entertainment Weekly that the character’s humor came from the way he entertained his children and wife at home.

The ads gave him time to build Audition Secrets

By his August 2019 conversation with Seales, Guarini said the national campaign had given him “a little bit of breathing room.” He could consider the work he wanted to develop and the lessons he wanted to pass on. That year he founded The Warrior Artist Alliance, sharing advice with performers through podcasts, blogs and training programs. His Audition Secrets podcast introduction appeared on June 19, 2019. He planned conversations with colleagues and theater veterans about career choices, challenges and advice. The introduction also promoted his Audition Secrets book, already available in audio, electronic and printed editions.

Prince Charming took him into Britney Spears songs

Guarini played Prince Charming in the 2021 world premiere of Once Upon a One More Time and returned for its Broadway production in 2023. The Britney Spears musical opened June 22 at the Marquis Theatre. In an August interview with Broadway Direct, he described spending six years developing the character. The prince began as a villain, and the creative team gradually gave him room to question the behavior he had learned. Guarini said playing Prince Charming as a biracial actor mattered to him because of the representation he had wanted as a child. The role also let him find comedy inside familiar fairy tales.

Cat Burglar carried his voice into SuperKitties

In 2023, Guarini voiced Cat Burglar in SuperKitties. The Disney series followed four superhero kittens who protected Kittydale and taught lessons about kindness, friendship and problem-solving. He discussed the new role and his approach to the series with Art Eddy on The Art of Fatherhood podcast in January that year, alongside a conversation about raising his children. His connection to the series continued into 2025: a September casting announcement named him among the returning guest voices for season three. The season’s Su-Purr-Wild story was set in the Kittydale Wild Jungle, where the kittens would meet a wildcat named Willa.

By 2025, he was coaching speakers and business owners

By May 2025, Guarini’s work included public speaking and confidence coaching for creatives, entrepreneurs and speakers through Profit Under Pressure LLC. His talks included The Confidence to Fail and The Celebrity Code. He spoke at schools and conferences and continued working with young performers through The Warrior Artist Alliance. In an interview with The Global Discussion, he explained that understanding the business side of a performing career formed part of his approach. He also described a daily routine that included guided meditation and time to rest. His coaching work extended the teaching he had begun through Audition Secrets.

His confidence book arrived in October 2026

Entrepreneur Press published Center Stage Confidence: How to Own Your Story and Command Any Room on October 6, 2026. The book used the steps of making a show, from workshops and previews to the dressing room, to organize practical advice. Speaking with TheaterMania on October 21, Guarini explained his interest in creating work that could keep helping people while he was away from the stage. The book included personal stories and questions and answers with theater colleagues. His central claim connected the audition room, American Idol, Lil’ Sweet and Cat Burglar: “Confidence is a learnable skill.”

• Justin Guarini: career and music
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