After honing her skills in youth theater, Reeser moved to Los Angeles, took acting classes at UCLA and studied the business as an intern to a casting director. In her 20s, she won her first television role as an alien on "Star Trek: Voyager" (2001); the following year, she starred as Marcia Brady in The Brady Bunch in the White House.

Reeser first gained a following as the scheming Taylor Townsend on the hit teen drama "The O.C.," appearing on the show's third and fourth seasons. She also showed off her singing chops as a spoiled mall owner's daughter in the made-for-television musical The American Mall (2008) and played a goddess living among human frailty in the CW dramedy "Valentine."