Gomez began her acting career at age seven, playing Gianna on Barney & Friends. She said that she learned "everything" about how to act while on the show. Season 7 of Barney & Friends, when Selena Gomez was on the show, was held up for some time. Because of this, the episodes featuring Gomez did not air until she was in 5th grade. This resulted in some mild controversy/confusion as to whether she was on Barney in the 5th grade or the 1st grade. In 2004, Gomez was discovered by the Disney Channel in a nation wide scouting. She appeared as a guest star on The Suite Life of Zack & Cody and Hannah Montana before being cast in Wizards of Waverly Place as one of the main characters, Alex Russo. She also appears in the 2009 Disney Channel movie based on the show. The movie drew 11.4 million viewers for its premiere, which is currently Disney Channel's second highest rated movie. In 2008, Gomez appeared in Another Cinderella Story, the direct-to-DVD sequel to the 2004 Hilary Duff film, opposite Drew Seeley. In its January 2009 television debut on ABC Family, it drew 5.3 million viewers and was ranked as the month's number one cable movie across all key demographics. She also had a minor voiceover role as one the Mayor's ninety-six daughters in Horton Hears a Who! which released in March of that year. In April, Forbes listed Gomez as one of its "Eight Hot Kid Stars To Watch." On October 30, 2008, she launched a production company, July Moon Productions, and teamed with XYZ Films to create star vehicles for her. In 2009, she appeared in the Disney Channel movie, Princess Protection Program with Demi Lovato. The film drew 8.5 million viewers for its premiere, the fourth-highest for a Disney Channel Original Movie. In 2008, Gomez recorded a cover of "Cruella de Vil" for DisneyMania 6, three songs for the Another Cinderella Story soundtrack, and "Fly to Your Heart" for the animated film Tinker Bell. In July 2008, she signed a record deal with Hollywood Records. She also had a cameo in the Jonas Brothers music video for "Burnin' Up". During an interview with MTV in August 2008, she said of her future music career: I'm going to be in a band — no Selena Gomez stuff. I'm not going to be a solo artist. I think that I don't want my name attached to it. I will be singing, and I'm learning drums and playing electric guitar. In 2009, Gomez recorded "One and the Same" for Princess Protection Program as a duet with her co-star Demi Lovato, four songs for the Wizards of Waverly Place soundtrack, and "Whoa Oh!" with Forever the Sickest Kids. Gomez with her band, Selena Gomez & The Scene released their debut studio album, Kiss & Tell on September 29, 2009.
Gomez was involved in the UR Votes Count campaign which helped encourage teenagers learn more about their 2008 Presidential candidates (Barack Obama and John McCain). In October 2008, Gomez was named a spokesperson for UNICEF's 2008 Trick-or-Treat campaign, which encouraged children to raise money on Halloween to help children around the world. She said that she was "extremely excited" to "encourage other kids to make a difference in the world." In October 2008, Gomez participated in St. Jude's Children's Hospital "Runway For Life" benefit. Gomez is a spokesperson for Borden Milk; she is featured in the campaign's print and television ads. She is the ambassador of DoSomething.org after being involved with the charity Island Dog, which help dogs in Puerto Rico. She got involved while filming Wizards of Waverly Place: The Movie in Puerto Rico. Gomez is a spokesperson for State Farm Insurance, and is featured in their TV commercials; which air on the Disney Channel, to raise awareness of being a safe driver. Gomez has been named the youngest UNICEF ambassador. In her first official field mission, Gomez traveled to Ghana on September 4, 2009 for a week to witness first-hand the stark conditions of vulnerable children that lack vital necessities including clean water, nourishment, education and healthcare. Gomez on her new role: "Every day 25,000 children die from preventable causes. I stand with UNICEF in the belief that we can change that number from 25,000 to zero. I know we can achieve this because every moment, UNICEF is on the ground providing children with the lifesaving assistance needed to ensure zero becomes a reality." Gomez was named spokesperson for UNICEF's 2009 Trick-or-Treat campaign, for the second year in a row, which encouraged children to raise money on Halloween to help children around the world.