Park made his acting debut in the 2003 short film Dragon of Love (as the main character, Joel), which won the Best Short Film at the 2003 Hawaii International Film Festival. He has appeared in feature films such as Larry Crowne, Dinner for Schmucks, and The Five-Year Engagement. He appeared in various independent film projects such as Quentin Lee's The People I've Slept With (2009) and starred and co-wrote the feature film American Fusion (2005).
In 2005 Park co-wrote and starred in the feature film American Fusion directed by Frank Lin, which won the Audience Award at the Hawaii International Film Festival. He has also created, directed, written, and starred in several short internet series for Channel 101, including Dr. Miracles, The Food, and Dumb Professor.
Park has made guest appearances on television shows including Community," "Curb Your Enthusiasm, New Girl, The Office, ER, CSI: Crime Scene Investigation, Four Kings, Las Vegas, House, iCarly, Cold Case, and Reno 911!. He appeared as Martin Fukanaga on Supah Ninjas and was a cast member on MTV's Wild 'n Out. In 2007, he regularly appeared as an actor in the filmmaking reality show On the Lot.
Park has been featured in ads for HBO Go, Ally Financial, and the 2011 Father's Day Verizon Droid commercial. He plays a "doggie daycare owner" in a print and online campaign for Chase Bank, which aired in early 2015.
In 2013 he wrote and starred in a series for Channel 101 featuring his baby daughter entitled Baby Mentalist. In Channel 101's bracket competition format for webseries, Baby Mentalist was voted number one the most times of any show at the time, ending with six episodes in 2013.
In 2014, Park played a company rep trying to recruit college students in Neighbors, co-starred in the Jason Segel/Cameron Diaz comedy, Sex Tape, which led to his being cast in The Interview (2014), portraying Kim Jong-un.
Park was featured in Wong Fu Productions' short film, Too Fast as Brandon, the web series Home Is Where the Hans Are as the stepfather and as Randall in their first feature film, Everything Before Us (2015).
