After an internship at a news station in Tulsa, she moved to Los Angeles where she began her professional career as a television host for the gaming network G4, primarily on the series Attack of the Show!

[6] Her mother, who is a Vietnamese woman of Chinese ancestry, arrived as a refugee in the United States in 1975 following the Vietnam War and settled in Oklahoma, where she met Munn's father.

When Munn was two years old, her parents divorced and her mother married a member of the United States Air Force.

[9] Munn's stepfather was then transferred to Yokota Air Base near Tachikawa in Tokyo, Japan, where she spent her formative years.

In 2004, she interned at Fox Sports Networks and worked as a sideline reporter for college football and women's basketball.

She appeared in rock band Zebrahead's music video for their song "Hello Tomorrow" as the love interest of lead singer Justin Mauriello.

[20] She also appeared in National Lampoon's Strip Poker, filmed at Hedonism II, a naturist resort in Negril, Jamaica, with Kato Kaelin.

[24] In 2006, Munn won a contest put out to the public to find a replacement for departing co-host Kevin Rose on the popular G4 network program Attack of the Show!

[25] On the show, she was featured with journalist Anna David in a segment called "In Your Pants", which deals with sex and relationship questions from viewers.

While working on Attack of the Show!, she hosted Formula D, a now defunct program about American drift racing, and an online podcast called Around the Net, formerly known as The Daily Nut, for G4.

[32] Her credentials were questioned by Irin Carmon of the website Jezebel, who suggested that Munn was better known as a sex symbol than as a comedian.

[38] Munn gained prominence in a lead role in Aaron Sorkin's drama series The Newsroom on HBO.

In the series, she played Sloan Sabbith, an economist who worked on the show's fictional news network, ACN, alongside lead anchor Will McAvoy (Jeff Daniels).

Beginning in January 2015, Munn voiced the character Phoebe Callisto on the Disney Junior animated series Miles from Tomorrowland.

[43] The same year, Munn had a leading role portraying a technical supervisor in the comedy film Office Christmas Party.

[46] Following the film's release, it was revealed that Munn's co-star, Steven Wilder Striegel, with whom she shared a scene, was a registered sex offender who had preyed on a 14-year-old girl.

[46] Munn subsequently had a lead role in the Netflix-released romantic comedy film Love Wedding Repeat (2020), a remake of the French feature Plan de Table,[47] and the film The Gateway (2021), about a social worker assigned to the care of the daughter of a single mother (played by Munn) who intervenes when the dad returns from prison and lures them into a life of crime.

[48] From 2021 to 2024, Munn voiced the supervillainness Akiko Yokohama / Lady Bullseye II in the adult animated series Hit-Monkey.

In a review for Time Out New York, Olivia Giovetti said that the book offers glimpses into Munn's life, but does not go into depth.

[better source needed][61] In February 2013, Munn fronted a PETA release of new footage showing cruelty to animals in Chinese fur farms.

[63] Munn was part of a roundtable discussion alongside Stop AAPI Hate co-founder Russell Jeung, RISE founder and CEO Amanda Nguyen with CBS News entitled "Asian Americans Battling Bias: Continuing Crisis.

However, after viewing footage from the New York City Police Department of alleged real-life exorcisms, she said "I'm a full believer [now].