Cosgrove's first television appearance was in 2001 as a 5-year old Lana Lang in the pilot of Smallville

As of May 2010, Cosgrove earned US$180,000 per episode of iCarly, making her the second highest paid child star on television.[2] She has been listed in the 2012 Guinness Book Of World Records as the Highest Paid Child Actress for iCarly.[3]

Following the success of iCarly, a soundtrack album was released in June 2008, in which she performed four songs. Cosgrove's debut album Sparks Fly was released on April 27, 2010.