Michalka rose to prominence with her starring role as Keely Teslow in the Disney Channel sitcom Phil of the Future (2004–2006).

She grew up in Seattle, Washington, and Southern California with her younger sister, Amanda Joy "AJ", who is also an actress and musician.

She started acting when she was five years old in church play productions her family attended outside Seattle, Washington and Thousand Oaks, California.

[12] In April 2010, The CW announced Michalka was cast in the main role of Marti Perkins on the cheerleading drama series Hellcats.

In 2013, Michalka appeared in the independent drama film, Crazy Kind of Love, alongside Eva Longoria, Virginia Madsen and Amanda Crew.

The movie was written and directed by her husband, Stephen Ringer, and premiered at the Los Angeles Film Festival on June 16, 2015.

In July 2007, their third album, Insomniatic, was released, featuring the Billboard top 20 hit single, "Potential Breakup Song".

The duo changed their name to 78violet and were set to release a fourth album in early 2010,[20] but the project never materialized following their departure from Hollywood Records.

In 2012, Michalka began dating independent film producer Stephen Ringer, whom she met on the set of Sequoia.