Munn was born and raised in Columbia, South Carolina, the daughter of Russell and Nadine Munn. Her mother, an elementary school teacher, encouraged her daughter in the arts by letting her take dance and singing lessons at an early age. Munn graduated from AC Flora High School and The College of Charleston. From there, she moved to New York, where she won a role in the Off-Broadway classic, The Fantasticks.
Munn's further auditions led to small roles in Hollywood productions; most notably in White Oleander alongside Michelle Pfeiffer and in Elizabethtown, directed by Cameron Crowe.
Munn's biggest break came in September 2003 when she got a co-starring role, opposite Amanda Bynes and Jennie Garth, on the sitcom What I Like About You, as one of Holly's best friends, Tina Haven. Although their characters are the same age, Munn is eleven-and-a-half years older than her co-star Bynes. Munn remained on the show for three seasons until the show ended on April 24, 2006.
Munn also has a level of notoriety for a recurring role as Caroline, Fez's borderline stalker girlfriend on That '70s Show.
Munn appeared in the ABC comedy series Carpoolers.
In 2009, Munn began a recurring role on One Tree Hill as Miss Lauren, Jamie Scott's teacher. Lauren begins dating Skills Taylor at the end of season 6. They broke up in season 7, because Skills got a job offer in Los Angeles. She later forms a close friendship with Mouth after they both split from their partners. After forming this bond, they begin a brief relationship, not wanting to hold his friendship with Skills against them. Skills soon discovers their relationship and but they are able to move on attempt to continue their relationship but it is short-lived. In the final season, Lauren starts a relationship with friend Quinn's ex-husband David Fletcher (played by Munn's real-life husband Scott Holroyd).
Munn began dating her childhood friend, actor Scott Holroyd in 2004. They became engaged in Paris in December 2006 and married on November 17, 2007 at the French Huguenot Church in Charleston, South Carolina. They reside in Los Angeles with their pet terrier, Buster Keaton. In November 2011 Munn announced, via her Twitter account, that she and Holroyd welcomed their son Nathan Powell Holroyd.
Munn lends her name and support to the non profit political organization Rock the Vote, where she is actively involved in encouraging young people to register to vote.
|2005||Elizabethtown||Desk Clerk Charlotte|
|2005||A Couple of Days and Nights||Tequila|
|2007||Farm Girl in New York||Mary|
|2010||Successful Alcoholics||Dianne||Short film|
|2011||I'm Having a Difficult Time Killing My Parents||Kayte||Short film|
|1999||Now and Again||Gretchen||Episode: "A Girl's Life"|
|2000||Now and Again||Gretchen||Episode: "The Bugmeister"|
|2000||Law & Order: Special Victims Unit||Emily Harlin||Episode: "Russian Love Poem"|
|2001–2006||That '70s Show||Caroline||Recurring role (10 episodes)|
|2001||2gether||Cindy||Episodes: "The Launch", "Kiss"|
|2002||St. Sass||Kimmy||TV film|
|2002||Inside Schwartz||Jackie||Episode: "Kissing Cousin"|
|2002||JAG||Sue Ellen Newton||Episode: "Odd Man Out"|
|2002||Boston Public||Janice Scott||Episode: "Chapter 38"|
|2003||Sweet Potato Queens||TV film|
|2003||Charmed||Wendy||Episode: "Sand Francisco Dreamin'"|
|2003–2006||What I Like About You||Tina Haven||Main role (59 episodes)|
|2007–2008||Carpoolers||Cindy||Main role (13 episodes)|
|2009||Untitled Family Plot||Jillian||TV pilot|
|2009–2012||One Tree Hill||Lauren||(21 episodes)|
|2010||Wright vs. Wrong||Tami Manly||TV film|
|2013||Family Tools||Clarissa||Episode: "Waiting for Mrs. Bichette"|
|2013||Dads||Anne||Episode: "Funny Girl"|
|2014 -||Nicky, Ricky, Dicky & Dawn||Anne Harper|
- Carpoolers' Allison Munn Weds Southern-Style - Weddings : People.com
- She married Scott Holroyd in 2007.