
Early work:
In 1995, Seyfried started her career as a child model at age eleven. At the beginning of her modeling career she signed with Image International Agency (IIA) in Allentown, Pennsylvania (where she lived at the time) before switching over to work at Bethlehem's Pro Model Agency and eventually signing with Wilhelmina agency in New York City, New York. Seyfried's modeling career ended when she was seventeen. During her modeling career she appeared in print ads for clothing companies; including Limited Too with Leighton Meester.
While modeling, Seyfried took voice lessons from eleven to seventeen. She trained with a Broadway voice coach for nearly five years. She spent two years training for classical opera and acted on stage in New York productions include a revival of Jim Jacobs and Warren Casey's musical Grease, Kenneth Grahame's “Wind in the Willows”, and Charles Dickens' A Christmas Carol. From there she began acting as an extra in the daytime drama television series Guiding Light; her role on the show was uncredited. In 2000, she originated the role of Lucinda Marie "Lucy" Montgomery #2 on the television show As the World Turns; appearing on the show as a recurring character, her role on the show lasted until 2001. After appearing in twenty-seven episodes, Seyfried left the show as a result of creative conflicts. From 2002 to 2003, Seyfried played the recurring role of Joni Stafford on the American Broadcasting Company (ABC) broadcasted show, All My Children; Seyfried appeared in a total of three episodes.
In the fall of 2003, Seyfried auditioned to play the mean-girl role of Regina George in the 2004 film Mean Girls; the role eventually went to Rachel McAdams, but the producers of the film picked Seyfried to play one of Regina's two dim-witted "plastic" friends and sidekicks, Karen. Seyfried had reportedly received the role of Karen over Ashley Tisdale. The film, which Seyfried co-starred alongside Lohan, McAdams, centered on Cady trying to 'take down' the "plastics" at her high school. Mean Girls was a block-buster box-office success, making over 129 million in its theatrical run. Seyfried's performance in the film earned her, along with Lohan and McAdams, a MTV Movie Award in the category of "Best On-Screen Team." Mean Girls marks Seyfried's feature film debut.
Also in 2004, continuing her television career, Seyfried auditioned to play the title character on UPN's popular television show Veronica Mars, the role eventually went to Kristen Bell. Despite not receiving the role she had originally auditioned for, she won the role of the title character's murdered best friend Lilly Kane. Although her character was only shown in flashbacks, Lily was vital part of the first season's plot and made Seyfried one of the show's 'familiar faces'. Seyfried appeared in ten episodes from 2004–2005. In 2005, she played the lead character Samantha in one of the nine parts in the film Nine Lives, the film centers on nine short films with different themes with an ensembled cast. Writer-director Rodrigo Garcia wrote Samantha's part specifically with Seyfried in his mind for the role. For her performance in the film, Seyfried won an award from the Locarno International Film Festival, for Best Actress, which she shared with the film's other female leads. The same year she played supporting character Mouse in American Gun. In 2006 Seyfried appeared in five episodes on Wildfire as Rebecca and had lead role as Chrissy in Gypsies, Tramps & Thieves and a minor role as Julie Beckley in Alpha Dog. From 2004 to 2006, Seyfried made multiple guest appearances on television series, notably including House, M.D., Justice, Law & Order: Special Victims Unit and CSI: Crime Scene Investigation.
While modeling, Seyfried took voice lessons from eleven to seventeen. She trained with a Broadway voice coach for nearly five years. She spent two years training for classical opera and acted on stage in New York productions include a revival of Jim Jacobs and Warren Casey's musical Grease, Kenneth Grahame's “Wind in the Willows”, and Charles Dickens' A Christmas Carol. From there she began acting as an extra in the daytime drama television series Guiding Light; her role on the show was uncredited. In 2000, she originated the role of Lucinda Marie "Lucy" Montgomery #2 on the television show As the World Turns; appearing on the show as a recurring character, her role on the show lasted until 2001. After appearing in twenty-seven episodes, Seyfried left the show as a result of creative conflicts. From 2002 to 2003, Seyfried played the recurring role of Joni Stafford on the American Broadcasting Company (ABC) broadcasted show, All My Children; Seyfried appeared in a total of three episodes.

Also in 2004, continuing her television career, Seyfried auditioned to play the title character on UPN's popular television show Veronica Mars, the role eventually went to Kristen Bell. Despite not receiving the role she had originally auditioned for, she won the role of the title character's murdered best friend Lilly Kane. Although her character was only shown in flashbacks, Lily was vital part of the first season's plot and made Seyfried one of the show's 'familiar faces'. Seyfried appeared in ten episodes from 2004–2005. In 2005, she played the lead character Samantha in one of the nine parts in the film Nine Lives, the film centers on nine short films with different themes with an ensembled cast. Writer-director Rodrigo Garcia wrote Samantha's part specifically with Seyfried in his mind for the role. For her performance in the film, Seyfried won an award from the Locarno International Film Festival, for Best Actress, which she shared with the film's other female leads. The same year she played supporting character Mouse in American Gun. In 2006 Seyfried appeared in five episodes on Wildfire as Rebecca and had lead role as Chrissy in Gypsies, Tramps & Thieves and a minor role as Julie Beckley in Alpha Dog. From 2004 to 2006, Seyfried made multiple guest appearances on television series, notably including House, M.D., Justice, Law & Order: Special Victims Unit and CSI: Crime Scene Investigation.
Film:
2004
Mean Girls
2005
Nine Lives
American Gun
2006
Alpha Dog
Gypsies, Tramps & Thieves
2008
Solstice
Mamma Mia!
Official Selection
2009
Boogie Woogie
Jennifer's Body
2010
Dear John
Chloe
Letters to Juliet
2011
A Woman of No Importance
2004
Mean Girls
2005
Nine Lives
American Gun
2006
Alpha Dog
Gypsies, Tramps & Thieves
2008
Solstice
Mamma Mia!
Official Selection
2009
Boogie Woogie
Jennifer's Body
2010
Dear John
Chloe
Letters to Juliet
2011
A Woman of No Importance

2000–2001
As the World Turns
2002–2003
All My Children
2004
Law & Order: Special Victims Unit
2004–2005
Veronica Mars
2005
House M.D.
2006
Justice
Wildfire
CSI: Crime Scene Investigation
2006–2010
Big Love
2008
American Dad!