2005–2009: Breakthrough with films and music
Tisdale joined the main cast of the Disney Channel series The Suite Life of Zack & Cody in 2005, and would continue to star in the series until its conclusion in 2008. The show proved to be a hit for the network, and earned Tisdale a Nickelodeon UK Kids' Choice Awards. Tisdale had her breakout role as Sharpay Evans in the Disney Channel film High School Musical (2006). The film was the network's most successful film of 2006, receiving 7.7 million viewers upon its premiere. The soundtrack for the film, featuring numerous contributions from Tisdale, went on to sell over three million copies in the United States alone. The song "What I've Been Looking For" (2006), a duet with Lucas Grabeel, became her first top 40 hit on the Billboard Hot 100, and was certified gold by the Recording Industry Association of America (RIAA). Tisdale, along with the rest of the cast, embarked on the High School Musical: The Concert (2006–2007) tour to promote the film. She met dancer Jared Murillo while working on High School Musical, and the two later dated for two years; they split up in 2009. During this time, Tisdale began appearing on soundtracks for the Disney Channel, and released a cover of "Kiss the Girl" (2006) to promote The Little Mermaid.
With the success of High School Musical, Tisdale was offered a recording contract from Warner Bros. Records; she began working on her debut studio album in 2006. "Be Good to Me" (2006) was released as the album's lead single, with "He Said She Said" (2007) being released shortly afterwards as the second single. Tisdale's debut album, Headstrong (2007), was released in February; the album featured elements of dance-pop and hip-hop music. The album sold 64,000 copies in its first week of release in the United States, debuting at number five on the Billboard 200. The project was a commercial success, selling over 500,000 copies in the country. "He Said She Said" was later re-released as the album's second single to promote the album, and went on to earn a gold certification from the RIAA. The album's final two singles were released exclusively in select European territories. Tisdale embarked on her Headstrong Tour Across America to promote the album. She also co-executive produced a documentary, There's Something About Ashley (2007), documenting the recording of the album and the production of her music videos.
Tisdale reprised her role as Sharpay Evans in High School Musical 2 (2007). The film was viewed by seventeen million people during its premiere, making it the most-watched movie on cable television. She received positive reviews for her performance in the film, which earned two Primetime Emmy Awards nominations. The film's soundtrack topped the Billboard 200, selling 615,000 copies in its first week of release. Tisdale was later cast in the animated Disney Channel series Phineas and Ferb, which debuted immediately after High School Musical 2, as the voice of Candace Flynn. The series debuted to ten million viewers and became the most-watched animated series among kids and tweens in 2010. Phineas and Ferb has also received acclaim by critics and has won three Primetime Emmy Awards. Tisdale remained on the series until its conclusion in 2015, appearing in various television films in the role as well.
In 2008, Tisdale formed her own production company, Blondie Girl Productions. The television film Picture This (2008) marked Tisdale's debut as an executive producer and as an actress in a leading role; she played Mandy Gilbert, an unpopular and bullied teenager. The film premiered on ABC Family in 2008 to 4.3 million viewers. Tisdale again appeared as Sharpay Evans in High School Musical 3: Senior Year, which was released in October 2008. It earned $42 million in its domestic opening weekend, and grossed a total of $255 million worldwide. Her performance in the film earned her critical acclaim, earning an MTV Movie Award for "Breakthrough Performance Female" in 2009. Owen Gleiberman of Entertainment Weekly labeled her one of film's breakout stars, and Mark Kermode said Tisdale was 2008's "best supporting actress".
Tisdale began working on her second studio album in 2008, taking more creative control over the record than with her last. The album served as a musical departure from her prior record, with Tisdale hoping to attain a more "rock-oriented" and "edgier" sound. The project was preceded by the release of "It's Alright, It's OK" (2009), which went on to have some success in countries such as Austria and Germany. Her second studio album, Guilty Pleasure (2009), was released in select territories on June 11, 2009; it would not receive a release in the United States until July 28. The album sold an estimated 25,000 copies in its first week of release, debuting at number twelve on the Billboard 200. The album's second and final single, "Crank It Up" (2009), was released in select European territories. Tisdale parted ways with the label following the release of the record. During this time, Tisdale began dating director Scott Speer, who had directed her previous music videos; the couple would break up in 2011.
Tisdale also starred in the film Aliens in the Attic (2009) as teenager Bethany Pearson. Although she is credited as one of the main characters, The New York Times said Tisdale "spends much of the film off-screen". The film was a minor success in box offices, grossing $60 million worldwide.
