Mullen was born and raised in Santa Barbara, California to parents Ted, a biologist, and Stefani and attends Oak Park High School. He has a younger brother, Aidan.
Mullen has been acting since he was 4, starting in local productions and theater groups, but only professionally since he got his role on Andi Mack.
He wrote, produced, directed, and starred in short film, Me, My Phone, and I, which was featured in the 2017 All-American High School Film Festival and the 2018 Santa Barbara International Film Festival.
In 2019, he guest starred in an episode of American Housewife. He has an upcoming film that he has directed and starred in, Unforgettable.
Mullen is passionate about environmentalism. He is the vice president of Tomorrows Green, a non-profit environmental organization based in Santa Barbara. He teamed up with activist group Fridays for Future in May 2019 in the students' strike for the climate.
|2017||Me, My Phone, & I||Jeremy||Wrote, directed, and produced|
|2017-2019||Andi Mack||TJ Kippen||Recurring role|
|2019||American Housewife||Jason||Episode: "The Things You Do"|