Born in Houston, Texas, and raised in Charleston, West Virginia, Garner studied theater at Denison University and began acting as an understudy for the Roundabout Theatre Company in New York City.
She made her screen debut in the television adaptation of Danielle Steel's romance novel Zoya in 1995.
Garner works as an activist for early childhood education and is a board member of Save the Children USA.
She is the co-founder and chief brand officer of the organic baby food company Once Upon a Farm.
She is also an advocate for anti-paparazzi campaigns among children of celebrities.