Born in Amarillo, Texas to Korean-American parents, Cho spent most of her childhood years in Dallas and her late teenage years in Minnesota together with her younger brother. As a child, she was often a target for bullying and was hospitalized twice for injuries after being physically attacked, saying that "I had two teeth knocked out, a chipped tooth, [and] I still wear a wire . . . my entire face was cut up. It was bad. It took me six months to completely recover." Growing up in areas with few ethnic minorities, she was made to feel like an outsider. She attended Apple Valley High School and was a highly involved student, saying that "My parents put me in dance classes, martial arts, sports, spelling bees, painting, music, cello; all sorts of things." It wasn't until she moved to the University of Illinois at Urbana–Champaign where she majored in psychology that she connected with her Asian American background. It was there that she attended her first drama classes and developed an interest in the profession, noting "theater was the first time I felt like I could open up and be someone I could only imagine to be".
In 2004, Cho entered and won the Miss Korea Chicago competition, giving her the opportunity to take part in the Miss Korea Pageant in Seoul, South Korea. The latter proved to be a disappointing experience as she was urged to get plastic surgery. After graduating in 2007 she spent the summer of that year in Kenya on a two-month humanitarian trip. Upon her return, she decided to move to Los Angeles where she worked odd jobs while trying to pursue a career in acting.
In 2010, the cosmetic brand Clinique announced Cho as the model for their newest advertisement campaign in Asia. The campaign was launched in mid-November 2010. Clinique was reported to have stated that they "selected Cho not because she was Korean, but because she had the beauty to represent Asia". Cho modeled for Reebok Korea in 2010 and for Nike Japan in 2008. She has also modeled for Apple and Alexander McQueen and appeared in Vogue, Purple Fashion and Nylon Magazine.
Cho has appeared in films, television series and commercials in the United States and Asia.
Cho is best known for her lead role as Kira Yukimura, a kitsune, on the MTV series Teen Wolf.
In 2011 she appeared in the role of Pru, a friend of Paige McCullers (Lindsey Shaw) in Season 1, Episode 20 ("Someone to Watch Over Me"), of the ABC Family show Pretty Little Liars. The episode originally aired on March 7, 2011. In 2011 she also appeared in the role of Gia in the monster film Mega Python vs. Gatoroid, directed by Mary Lambert. In 2009 Cho appeared in Season 5, Episode 19 ("Communication Breakdown"), of the CBS show CSI: NY, in the supporting role of Gahee Paik, the daughter of a Korean father suspected of murder. The episode originally aired on March 25, 2009. In 2008 Cho played the grown-up lead of Hyori (the younger version being played by Megan Lee) in the short film My First Crush, directed by Rocky Jo. She has also appeared in the webseries KTown Cowboys. Cho also starred in the 2010, 35-minute YouTube feature Agents of Secret Stuff presented by Nigahiga and Wong Fu Productions.
In 2014, Cho joined the TV series Teen Wolf as Kira, starting as a recurring character in season 3 but promoted to a main cast role in season 4. In April 2016, ahead of her talk at University of Illinois at Chicago for Asian American Awareness Month, Arden Cho posted a YouTube video on her personal channel revealing that she would not return for season 6 of Teen Wolf. Arden is currently shooting for Honered Movie, which she has mentioned on her Instagram and Twitter accounts.
On February 22, 2011, Cho released the single "I'm Just a Girl" on iTunes. Cho was the co-writer, composer and singer on the single; Ed Huang was co-writer and music producer. On February 25, 2011, Cho published a self-produced music video for the single on YouTube featuring Tim Lacatena. Musical videos featuring her collaborations with other YouTube figures including Gerald Ko, Jason Chen, Ken Salomon and Megan Lee appear on her other, more informal ardenBcho YouTube account. Another musical collaboration to which Cho has lent her voice is the non-commercial Mark Allen song "I Once Knew".