In 2003, she entered R U All That?: Nickelodeon's Search for the Funniest Kid in America competition and won the highly coveted spot as a regular performer on All That.
As part of her audition, Christina was asked to do a skit in which she met Jay Leno. She had never heard of Leno because she had never stayed up late, so she said, "Who the heck is Jay Leno?" and instead pretended to talk to Leno's bodyguard.
When asked if she thought she was going get into the All That cast, Christina responded, "I thought I had no chance!" with a laugh.
Christina joined the cast of All That in Season 9 after Bryan Hearne left the show. Christina Kirkman replaced Jamie Lynn Spears as the youngest cast member of All That. Christina remained on All That until the show was canceled.
After All That came to an end, Christina returned to Massachusetts where she experienced bullying. This caused her to temporarily stop acting to focus on school. She graduated from Bishop Finwick High School. In 2015, she graduated from Emerson College in Boston, Massachusetts where she studied broadcast journalism and also participated in several different on campus productions.
After completing college, Christina moved back to Los Angeles to pursue acting and as of 2016, she completed filming the movie "Night Shadow".