Seyfried started her career as a model at age eleven. From there she went on to acting uncredited in the daytime drama Guiding Light. In 2000, she originated the role of Lucy Montgomery on As the World Turns. From 2002 to 2003, she played the role of Joni Stafford on ABC's All My Children.
In 2004, Seyfried achieved a breakthrough when she was cast as the most dimwitted of the Plastics, Karen Smith, in the popular teen film Mean Girls. In Mean Girls, she initially auditioned for the role of Regina George. She became the original casting choices for both the roles of Regina George and Cady Heron.[citation needed] She was then cast as Regina George's sidekick, and supporting lead, Karen Smith. The other roles later went to Rachel McAdams and Lindsay Lohan, respectively. In 2005, she played the lead character in one of the nine parts in the movie Nine Lives.
Continuing her television career, Seyfried was cast in UPN's Veronica Mars as the title character's murdered best friend Lilly Kane. In her role as Lilly, she appeared on the show through a series of flashbacks, dreams and visions, which portrayed her as a wild, stylish, and bubbly teenage daughter of a business executive. While appearing often during Mars' first season, she also appeared briefly in the second season's premiere and finale. Seyfried originally auditioned for the title role on Veronica Mars, but lost the place to Kristen Bell and she ended up winning the role of Lilly Kane.
Seyfried has had minor guest roles on House, M.D., Justice, Law & Order: Special Victims Unit and CSI: Crime Scene Investigation and as Rebecca on Wildfire. Seyfried also portrays a main character, Sarah Henrickson, in the series Big Love.
She played supporting roles in the 2007 films Alpha Dog and Solstice, and had her first lead role as the bride Sophie in the film version of the musical Mamma Mia!. Her musical performance in that film is also available on Mamma Mia! The Movie Soundtrack. Seyfried recorded a "Gimme! Gimme! Gimme! (A Man After Midnight)" music video specially for Mamma Mia!.
Seyfried joined the cast of the dark horror film Jennifer's Body in February 2008, which began filming in March 2008, playing the title character's best friend. Seyfried has several films in post-production. Titles include "Chloe", "Dear John", and "Boogie Woogie". “Chloe” is a remake of the French film Nathalie, and also stars Liam Neeson and Julianne Moore. Seyfried was scheduled to play the lead in Zack Snyder's new film Sucker Punch, but had to drop out due to scheduling conflicts with Big Love.
She is slotted to star in the both the forthcoming film version of A Woman of No Importance and Gary Winick's Letters To Juliet, which she's shooting in the italian city of Verona, where the tragic story of Romeo and Juliet was set by William Shakespeare.
Amanda how is it going? I hope you are fine now! I can't wait till see the new film you are in: "Dear John"! But where I live I can't see it untill 26 of March :( Well I'll wait for it a little more *_*! Amanda is it true that you will be in "The Girl With the Red Riding Hood" ?? I hope you'll answer me =)
Hey Amanda, you looked really great at the Oscars!! When you were up on stage, you looked like you were having the time of your life! Have a good one.Thomas.
hi pretty Amanda, I had no idea that you were the same girl from Mean Girls and Alpha Dog, until I saw you on Chelsea Lately, and then it dawned on me. You're like a completely different person now, which is proof you're a talented actress
Hi amanda just want to say that I enjoyed that Dear John movie!!! It was so awesome!!!!!!!!!!! i really like the romance parts of it. I cried during some sad scenes too. It was the best movie I have seen even though it was sad at times, I still enjoyed it! You are not a mean girl you are a talented one! :)
Hey! How' s Life treating you, my friend? And this 2010?? I have so many plans and dreams in Life! I swear: nothing will prevent me from completing them! Upon My Word. Michela Luise