In 2004, he starred in his first film role as Ethan Dolloway in the third installment of the Halloweentown series Halloweentown High. He subsequently reprised this role in the series' fourth installment Return to Halloweentown. Grabeel has made television guest appearances in TV series such as Boston Legal, 'Til Death, and Veronica Mars. On Smallville, he portrayed a young Lex Luthor. In 2006, he was cast in the role of Ryan Evans, the fraternal twin brother of Sharpay Evans (played by Ashley Tisdale), in the Emmy Award-winning made-for-television Disney movie High School Musical. He reprised his role in the television sequels High School Musical 2 and High School Musical 3: Senior Year. In 2007, he joined co-stars Vanessa Hudgens, Ashley Tisdale, Corbin Bleu and Monique Coleman on the 51-date High School Musical: The Concert. In early 2009, Billboard believed that Grabeel and Tisdale's track "I Want It All" should be nominated for an Oscar in the Best Original Song category however, the song did not make the final shortlist. During his time in High School Musical, Grabeel (along with his co-stars) had a total of six tracks chart in the Billboard Hot 100.